Millimeter channel reactors(MCRs)have received increasing attention because of their ability to enhance treatment capacity in addition to the advantages of microchannels.In previous studies,less work has been conducte...Millimeter channel reactors(MCRs)have received increasing attention because of their ability to enhance treatment capacity in addition to the advantages of microchannels.In previous studies,less work has been conducted on the micromixing process and enhancement strategies for non-Newtonian fluids in MCRs.In this study,the micromixing efficiency in MCRs was experimentally investigated using CMC(carboxymethyl cellulose sodium)aqueous solution to simulate a non-Newtonian fluid,and the enhanced mechanism of micromixing efficiency by the addition of internals and rotation was analyzed by computational fluid dynamics(CFD)simulations.The results show that in the conventional channel,increasing the flow rate improves the micromixing efficiency when the CMC concentration is low.However,when the CMC concentration is higher,the higher the flow rate,the lower the micromixing efficiency.The highest micromixing efficiency is obtained for the rotationally coupled inner components,followed by the single rotation and the lowest is for the internals only.CFD simulations reveal that the most effective way to improve the micromixing efficiency of non-Newtonian fluids with shear-thinning behavior is to increase the shear force in the reactor,which effectively reduces the apparent viscosity.These results provide the theoretical foundation for enhancing the micromixing process of non-Newtonian fluids in small-size reactors.展开更多
Bubble breakup at T-junction microchannels is the basis for the numbering-up of gas−liquid two-phase flow in parallelized microchannels. This article presents the bubble breakup in viscous liquids at a microfluidic T-...Bubble breakup at T-junction microchannels is the basis for the numbering-up of gas−liquid two-phase flow in parallelized microchannels. This article presents the bubble breakup in viscous liquids at a microfluidic T-junction. Nitrogen is used as the gas phase, and glycerol-water mixtures with different mass concentration of glycerol as the liquid phase. The evolution of the gas−liquid interface during bubble breakup at the microfluidic T-junction is explored. The thinning of the bubble neck includes the squeezing stage and the rapid pinch-off stage. In the squeezing stage, the power law relation is found between the minimum width of the bubble neck and the time, and the values of exponents α1 and α2 are influenced by the viscous force. The values of pre-factors m_(1) and m_(2) are negatively correlated with the capillary number. In the rapid pinch-off stage, the thinning of the bubble neck is predominated by the surface tension, and the minimum width of the bubble neck can be scaled with the remaining time as power-law. The propagation of the bubble tip can be characterized by the power law between the movement distance and the time, with decreasing exponent as increased liquid viscosity.展开更多
Viscoelastic nanofluid flow has drawn substantial interest due to its industrial uses,including research and testing of medical devices,lubrication and tribology,drug delivery systems,and environmental remediation.Thi...Viscoelastic nanofluid flow has drawn substantial interest due to its industrial uses,including research and testing of medical devices,lubrication and tribology,drug delivery systems,and environmental remediation.This work studies nanofluid flow over a viscoelastic boundary layer,focusing on mass and heat transmission.An analysis is performed on the flow traversing a porous sheet undergoing nonlinear stretching.It assesses the consequences of viscous dissipation and thermal radiation.The scientific nanofluid framework laid out by Buongiorno has been exploited.The partial differential equations illustrating the phenomena can be transfigured into ordinary differential equations by utilizing appropriate similarity transformations.The simplified equations are unmasked using the Homotopy Analysis Method(HAM),a semi-analytical approach designed to solve nonlinear ordinary and partial differential equations commonly encountered in numerous scientific and engineering disciplines.Calculations are executed to ascertain the numerical solutions related to temperature,concentration,and velocity fields,accompanied by the skin friction coefficient,local Nusselt number,and local Sherwood number.Visualizations of the results are accompanied by pertinent explanations grounded in scientific principles.The temperature distribution and corresponding thermal layer have been enhanced due to radiative and viscous dissipation characteristics.Additionally,it has been noted that a delay in fluid movement results from an improvement in the porous medium parameter and magnetic field values.A falling trend in the Nusselt number is observed as the Eckert and thermophoresis parameters increase.The current numerical results have been effectively validated against previous difficulties.展开更多
Viscoelastic solids,such as composite propellants,exhibit significant time and rate dependencies,and their fracture processes display high levels of nonlinearity.However,the correlation between crack propagation and v...Viscoelastic solids,such as composite propellants,exhibit significant time and rate dependencies,and their fracture processes display high levels of nonlinearity.However,the correlation between crack propagation and viscoelastic energy dissipation in these materials remains unclear.Therefore,accurately modeling and understanding of their fracture behavior is crucial for relevant engineering applications.This study proposes a novel viscoelastic phase-field model.In the numerical implementation,the adopted adaptive time-stepping iterative strategy effectively accelerates the coupling iteration efficiency between the phase-field and the displacement field.Moreover,all unknown parameters in the model,including the form of the phase-field degradation function,are identified through fitting against experimental data.Based on an introduced scaling factor,themechanical response behaviors of solid propellant dogbone specimens under cyclic loading,relaxation,and tension are analyzed,and the predictive capacity of the model is demonstrated by comparing the experimental data with the simulation results.Finally,modeling results for Mode-I and Mode-II crack propagation in single-edge-notched specimens indicate that the reduction of viscous energy dissipation will significantly increase the fracture growth rate,but under the same boundary conditions,the crack path remains unchanged.展开更多
Non-Darcian flow in rock fractures exhibits significant anisotropic characteristics,which can be affected by mechanical processes,such as cyclic shearing.Understanding the evolution of anisotropic nonDarcian flow is c...Non-Darcian flow in rock fractures exhibits significant anisotropic characteristics,which can be affected by mechanical processes,such as cyclic shearing.Understanding the evolution of anisotropic nonDarcian flow is crucial for characterizing groundwater flow and mass/heat transport in fractured rock masses.In this study,we conducted experiments on non-Darcian flow in single rough fractures under cyclic shearing conditions,aiming to analyze the anisotropic evolution of inertial permeability and viscous permeability.We established quantitative characterization models for the two types of permeability.First,we conducted cyclic shearing experiments on four sets of 24 rough rock fractures,investigating their shear characteristics.Then,we performed 480 non-Darcian flow experiments to analyze the anisotropic evolution of viscous permeability and inertial permeability of these rock fractures.The results showed that viscous permeability exhibited significant differences only in the orthogonal direction,while inertial permeability exhibited differences in both orthogonal and opposite directions.With increase in the shear cycles,the differences in the orthogonal direction gradually increased,while those in opposite direction gradually decreased.Finally,we established characterization equations for the two permeabilities based on the proposed directional geometric parameters and validated the performance of these equations with experimental data.These findings are useful for the quantitative characterization of the evolution of non-Darcian flow in fractures under dynamic loading conditions.展开更多
Maximizing the efficiency of thermal engineering equipment involves minimizing entropy generation,which arises from irreversible processes.This study examines thermal transport and entropy generation in viscous flow o...Maximizing the efficiency of thermal engineering equipment involves minimizing entropy generation,which arises from irreversible processes.This study examines thermal transport and entropy generation in viscous flow over a radially stretching disk,incorporating the effects of magnetohydrodynamics(MHD),viscous dissipation,Joule heating,and radiation.Similarity transformations are used to obtain dimensionless nonlinear ordinary differential equations(ODEs)from the governing coupled partial differential equations(PDEs).The converted equations are then solved by using the BVP4C solver in MATLAB.To validate the findings,the results are compared with previously published studies under fixed parameter conditions,demonstrating strong agreement.Various key parameters are analyzed graphically to assess their impact on velocity and temperature distributions.Additionally,Bejan number and entropy generation variations are presented for different physical parameters.The injection parameter(S<0)increases the heat transfer rate,while the suction parameter(S>0)reduces it,exhibiting similar effects on fluid velocity.The magnetic parameter(M)effectively decreases entropy generation within the range of approximately 0≤η≤0.6.Beyond this interval,its influence diminishes as entropy generation values converge,with similar trends observed for the Bejan number.Furthermore,increased thermal radiation intensity is identified as a critical factor in enhancing entropy generation and the Bejan number.展开更多
Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady ...Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady heat and mass transport properties.The hybrid nanofluid’s enhanced heat transfer efficiency is a major benefit in high-performance engineering applications.It is composed of two separate nanoparticles suspended in a base fluid and is chosen for its improved thermal properties.Thermal radiation,chemical reactions,a transverse magnetic field,surface stretching with time,injection or suction through the porous medium,and the effect of inclination,which introduces gravity-induced buoyancy forces,are all important physical phenomena that are taken into account in the analysis.A system of nonlinear ordinary differential equations(ODEs)is derived from the governing partial differential equations for mass,momentum,and energy by applying suitable similarity transformations.This simplifies the modeling procedure.The bvp4c solver in MATLAB is then used to numerically solve these equations.Different governing parameters modify temperature,concentration,and velocity profiles in graphs and tables.These factors include radiation intensity,chemical reaction rate,magnetic field strength,unsteadiness,suction/injection velocity,inclination angle,and nanoparticle concentration.A complex relationship between buoyancy and magnetic factors makes hybrid nanofluids better at heat transmission than regular ones.Thermal systems including cooling technologies,thermal coatings,and electronic heat management benefit from these findings.展开更多
Styrene-butadiene-styrene(SBS)modified asphalt(SA)has long found effective applications in road construction materials.When combined with fillers,SBS-modified asphalt has demonstrated promising resistance to fatigue c...Styrene-butadiene-styrene(SBS)modified asphalt(SA)has long found effective applications in road construction materials.When combined with fillers,SBS-modified asphalt has demonstrated promising resistance to fatigue cracking caused by temperature fluctuations and aging.In this study,molybdenum disulfide(MoS_(2))and polyphosphoric acid(PPA)were ground in naphthenic oil(NO)and subjected to mechanical activation to create PPAmodified MoS_(2),referred to as OMS-PPA.By blending various ratios of OMS-PPA with SBS-modified asphalt,composite-modified asphalts were successfully developed to enhance their overall properties.To assess the mechanical characteristics and stability of these modified asphalts,various methods were employed,including penetration factor,flow activation energy,fluorescence microscopy,and dynamic shear rheology.Additionally,the short-term aging performance was evaluated using Fourier transform infrared(FTIR)spectroscopy and nanoindentation tests.The results revealed a 3.7%decrease in the penetration-temperature coefficient for SAOMS compared to SA,while 1-SA-OMS-PPA showed an even greater reduction of 7.1%.Furthermore,after short-term aging,carboxyl group generation in SA increased by 5.93%,while SA-OMS exhibited a smaller rise of 1.36%,and 1-SA-OMS-PPA saw an increase of just 0.93%.The study also highlighted significant improvements in the hardness of these materials.The hardness change ratio for SA-OMS decreased by 43.08%,while the ratio for 1-SA-OMS-PPA saw a notable reduction of 65.16% compared to unmodified SA.These findings suggest that OMS-PPA contributed to improvements in temperature sensitivity,particle dispersibility,and resistance to shortterm aging in asphalts.The results hold significant promise for the future development of advanced asphalt-based materials with potential high-value applications in flexible pavements for highways.展开更多
This study rigorously examines the interplay between viscous dissipation,magnetic effects,and thermal radiation on the flow behavior of a non-Newtonian Carreau squeezed fluid passing by a sensor surface within a micro...This study rigorously examines the interplay between viscous dissipation,magnetic effects,and thermal radiation on the flow behavior of a non-Newtonian Carreau squeezed fluid passing by a sensor surface within a micro cantilever channel,aiming to deepen our understanding of heat transport processes in complex fluid dynamics scenarios.The primary objective is to elucidate how physical operational parameters influence both the velocity of fluid flow and its temperature distribution,utilizing a comprehensive numerical approach.Employing a combination of mathematical modeling techniques,including similarity transformation,this investigation transforms complex partial differential equations into more manageable ordinary ones,subsequently solving them using the homotopy perturbation method.By analyzing the obtained solutions and presenting them graphically,alongside detailed analysis,the study sheds light on the pivotal role of significant parameters in shaping fluid movement and energy distribution.Noteworthy observations reveal a substantial increase in fluid velocity with escalating magnetic parameters,while conversely,a contrasting trend emerges in the temperature distribution,highlighting the intricate relationship between magnetic effects,flow dynamics,and thermal behavior in non-Newtonian fluids.Further,the suction velocity enhance both the local skin friction and Nusselt numbers,whereas theWeissenberg number reduces them,opposite to the effect of the power-law index.展开更多
This paper investigates the mechanisms of rock failure related to axial splitting and shear failure due to hoop stresses in cylindrical specimens.The hoop stresses are caused by normal viscous stress.The rheological d...This paper investigates the mechanisms of rock failure related to axial splitting and shear failure due to hoop stresses in cylindrical specimens.The hoop stresses are caused by normal viscous stress.The rheological dynamics theory(RDT)is used,with the mechanical parameters being determined by P-and S-wave velocities.The angle of internal friction is determined by the ratio of Young's modulus and the dynamic modulus,while dynamic viscosity defines cohesion and normal viscous stress.The effect of frequency on cohesion is considered.The initial stress state is defined by the minimum cohesion at the elastic limit when axial splitting can occur.However,as radial cracks grow,the stress state becomes oblique and moves towards the shear plane.The maximum and nonlinear cohesions are defined by the rock parameters under compressive strength when the radial crack depth reaches a critical value.The efficacy and precision of RDT are validated through the presentation of ultrasonic measurements on sandstone and rock specimens sourced from the literature.The results presented in dimensionless diagrams can be utilized in microcrack zones in the absence of lateral pressure in rock masses that have undergone disintegration due to excavation.展开更多
To investigate the influence of different longitudinal constraint systems on the longitudinal displacement at the girder ends of a three-tower suspension bridge,this study takes the Cangrong Xunjiang Bridge as an engi...To investigate the influence of different longitudinal constraint systems on the longitudinal displacement at the girder ends of a three-tower suspension bridge,this study takes the Cangrong Xunjiang Bridge as an engineering case for finite element analysis.This bridge employs an unprecedented tower-girder constraintmethod,with all vertical supports placed at the transition piers at both ends.This paper aims to study the characteristics of longitudinal displacement control at the girder ends under this novel structure,relying on finite element(FE)analysis.Initially,based on the Weigh In Motion(WIM)data,a random vehicle load model is generated and applied to the finite elementmodel.Several longitudinal constraint systems are proposed,and their effects on the structural response of the bridge are compared.The most reasonable system,balancing girder-end displacement and transitional pier stress,is selected.Subsequently,the study examines the impact of different viscous damper parameters on key structural response indicators,including cumulative longitudinal displacement at the girder ends,maximum longitudinal displacement at the girder ends,cumulative longitudinal displacement at the pier tops,maximum longitudinal displacement at the pier tops,longitudinal acceleration at the pier tops,and maximum bending moment at the pier bottoms.Finally,the coefficient of variation(CV)-TOPSIS method is used to optimize the viscous damper parameters for multiple objectives.The results show that adding viscous dampers at the side towers,in addition to the existing longitudinal limit bearings at the central tower,can most effectively reduce the response of structural indicators.The changes in these indicators are not entirely consistent with variations in damping coefficient and velocity exponent.The damper parameters significantly influence cumulative longitudinal displacement at the girder ends,cumulative longitudinal displacement at the pier tops,and maximum bending moments at the pier bottoms.The optimal damper parameters are found to be a damping coefficient of 5000 kN/(m/s)0.2 and a velocity exponent of 0.2.展开更多
Studying immiscible fluid displacement patterns can provide a better understanding of displacement processes within heterogeneous porous media,thereby helping improving oil recovery and optimizing geological CO_(2) se...Studying immiscible fluid displacement patterns can provide a better understanding of displacement processes within heterogeneous porous media,thereby helping improving oil recovery and optimizing geological CO_(2) sequestration.As the injection rate of water displacing oil increases and the displacement pattern transits from capillary fingering to viscous fingering,there is a broad crossover zone between the two that can adversely affect the oil displacement efficiency.While previous studies have utilized phase diagrams to investigate the influence of the viscosity ratio and wettability of the crossover zone,fewer have studied the impact of rock heterogeneity.In this study,we created pore network models with varying degrees of heterogeneity to simulate water flooding at different injection rates.Our model quantifies capillary and viscous fingering characteristics while investigating porous media heterogeneity's role in the crossover zone.Analysis of simulation results reveals that a higher characteristic front flow rate within the crossover zone leads to earlier breakthrough and reduced displacement efficiency.Increased heterogeneity in the porous media raises injection-site pressure,lowers water saturation,and elevates the characteristic front flow rate,thereby expanding the extent of crossover zone.展开更多
This study explores free convective heat transfer in an electrically conducting nanofluid flow over a moving semi-infinite flat plate under the influence of an induced magnetic field and viscous dissipation.The veloci...This study explores free convective heat transfer in an electrically conducting nanofluid flow over a moving semi-infinite flat plate under the influence of an induced magnetic field and viscous dissipation.The velocity and magnetic field vectors are aligned at a distance from the plate.The Spectral Relaxation Method(SRM)is used to numerically solve the coupled nonlinear partial differential equations,analyzing the effects of the Eckert number on heat and mass transfer.Various nanofluids containing Cu,Ag,Al_(2)O_(3),and TiO_(2) nanoparticles are examined to assess how external magnetic fields influence fluid behavior.Key parameters,including the nanoparticle volume fraction ϕ,magnetic parameter M,magnetic Prandtl number Prm,and Eckert number Ec,are evaluated for their impact on velocity,induced magnetic field,and heat transfer.Results indicate that increasing the magnetic parameter reduces velocity and magnetic field components in alumina-water nanofluids,while a higher nanoparticle volume fraction enhances the thermal boundary layer.Greater viscous dissipation(Ec)increases temperature,and Al_(2)O_(3) nanofluids exhibit higher speeds than Cu,Ag,and TiO_(2) due to density differences.Silver-water nanofluids,with their higher density,move more slowly.The SRM results closely align with those from Maple,confirming the method’s accuracy.展开更多
The internal solitary wave(ISW)represents a frequent and severe oceanic dynamic phenomenon observed in the South China Sea,exposing marine structures to sudden loads.This paper examines the prediction model of interac...The internal solitary wave(ISW)represents a frequent and severe oceanic dynamic phenomenon observed in the South China Sea,exposing marine structures to sudden loads.This paper examines the prediction model of interaction loads between ISW and FPSO,accounting for varying attack angles and incorporating ISW theories.The research demonstrates that the horizontal and transverse forces on FPSO under internal solitary waves(ISWs)comprise wave pressure difference force and viscous force,while the vertical force primarily consists of vertical wave pressure difference force.The wave pressure difference force is determined using the Froude-Krylov equation.The viscous force is derived from the tangential particle velocity induced by ISW and the viscous coefficient.The viscous coefficient formula is obtained through regression analysis of experimental data with different ISW attack angles.The research reveals that the horizontal viscous coefficient C_(vx)decreases as Reynolds number(R_(e))increases,while the transverse viscous coefficient C_(vy)initially increases and subsequently decreases with the growth of the Keulegan-Carpenter number(KC).Moreover,changes in wave propagation direction significantly affect the extreme magnitudes of both horizontal and transverse forces,and simultaneously modify the transverse force orientation,while having minimal impact on the vertical force.Additionally,the forces increase with the ISW’s amplitude.For horizontal and transverse forces,a thinner upper fluid layer generates larger forces.Comparative analysis of experimental,numerical,and theoretical results indicates strong agreement between theoretical predictions and experimental and numerical outcomes.展开更多
Drying operations are of grave importance to realize the reduction and utilization of sewage sludge resources,but the conventional thermal evaporation drying(TED)technology presents challenges due to the need for a la...Drying operations are of grave importance to realize the reduction and utilization of sewage sludge resources,but the conventional thermal evaporation drying(TED)technology presents challenges due to the need for a large amount of thermal energy to conquer the phase-change latent heat of moisture.Herein,we report a non-phase change technology based on particle high-speed self-rotation in a cyclone for fast,low-temperature drying of viscous sludge with high-moisture contents.Dispersed phase medium(DPM)is introduced into the cyclone self-rotation drying(CSRD)reactor to enhance the dispersion of the viscous sludge.The effects of carrier gas temperature,feeding rate,size,and proportion of DPM particles in the drying process are systematically examined.Under optimal operating conditions,the weighted content of moisture in the viscous sludge could be reduced from 80%to 15.01%in less than 5 s,achieving a high drying efficiency of 95.79%.Theoretical calculations also reveal that 89.26%of the moisture is removed through non-phase change pathway,contributing to a 522-fold increase in the drying rate of CSRD compared to TED technology.This investigation presents a sustainable effective approach for high moisture viscous sludge treatment with low energy consumption and carbon emissions.展开更多
This study examines the intricate occurrences of thermal and solutal Marangoni convection in three-layered flows of viscous fluids,with a particular emphasis on their relevance to renewable energy systems.This researc...This study examines the intricate occurrences of thermal and solutal Marangoni convection in three-layered flows of viscous fluids,with a particular emphasis on their relevance to renewable energy systems.This research examines the flow of a three-layered viscous fluid,considering the combined influence of heat and solutal buoyancy driven Rayleigh-Bénard convection,as well as thermal and solutal Marangoni convection.The homotopy perturbation method is used to examine and simulate complex fluid flow and transport phenomena,providing important understanding of the fundamental physics and assisting in the optimization of various battery configurations.The inquiry examines the primary elements that influence Marangoni convection and its impact on battery performance,providing insights on possible enhancements in energy storage devices.The findings indicate that the velocity profiles shown graphically exhibit a prominent core zone characterized by the maximum speed,which progressively decreases as it approaches the walls of the channel.This study enhances our comprehension of fluid dynamics and the transmission of heat and mass in intricate systems,which has substantial ramifications for the advancement of sustainable energy solutions.展开更多
In this paper,we consider the initial boundary value problem for the 2-D hyperbolic viscous Cahn-Hilliard equation.Firstly,we prove the existence and uniqueness of the local solution by the Galerkin method and contrac...In this paper,we consider the initial boundary value problem for the 2-D hyperbolic viscous Cahn-Hilliard equation.Firstly,we prove the existence and uniqueness of the local solution by the Galerkin method and contraction mapping principle.Then,using the potential well theory,we study the global well-posedness of the solution with initial data at different levels of initial energy,i.e.,subcritical initial energy,critical initial energy and arbitrary positive initial energy.For subcritical initial energy,we prove the global existence,asymptotic behavior and finite time blowup of the solution.Moreover,we extend these results to the critical initial energy using the scaling technique.For arbitrary positive initial energy,including the sup-critical initial energy,we obtain the sufficient conditions for finite time blow-up of the solution.As a further study for estimating the blowup time,we give a unified expression of the lower bound of blowup time for all three initial energy levels and estimate the upper bound of blowup time for subcritical and critical initial energy.展开更多
The high thermal conductivity of the nanoparticles in hybrid nanofluids results in enhanced thermal conductivity associated with their base fluids.Enhanced heat transfer is a result of this high thermal conductivity,w...The high thermal conductivity of the nanoparticles in hybrid nanofluids results in enhanced thermal conductivity associated with their base fluids.Enhanced heat transfer is a result of this high thermal conductivity,which has significant applications in heat exchangers and engineering devices.To optimize heat transfer,a liquid film of Cu and TiO_(2)hybrid nanofluid behind a stretching sheet in a variable porous medium is being considered due to its importance.The nature of the fluid is considered time-dependent and the thickness of the liquid film is measured variable adjustable with the variable porous space and favorable for the uniform flow of the liquid film.The solution of the problem is acquired using the homotopy analysis method HAM,and the artificial neural network ANN is applied to obtain detailed information in the form of error estimation and validations using the fitting curve analysis.HAM data is utilized to train the ANN in this study,which uses Cu and TiO_(2)hybrid nanofluids in a variable porous space for unsteady thin film flow,and it is used to train the ANN.The results indicate that Cu and TiO_(2)play a greater role in boosting the rate.展开更多
Seismic fragility analysis of three-tower cable-stayed bridges with three different structural systems,including rigid system(RS),floating system(FS),and passive energy dissipation system(PEDS),is conducted to study t...Seismic fragility analysis of three-tower cable-stayed bridges with three different structural systems,including rigid system(RS),floating system(FS),and passive energy dissipation system(PEDS),is conducted to study the effects of connection configurations on seismic responses and fragilities.Finite element models of bridges are established using OpenSees.A new ground motion screening method based on the statistical characteristic of the predominant period is proposed to avoid irregular behavior in the selection process of ground motions,and incremental dynamic analysis(IDA)is performed to develop components and systems fragility curves.The effects of damper failure on calculated results for PEDS are examined in terms of seismic response and fragility analysis.The results show that the bridge tower is the most affected component by different structural systems.For RS,the fragility of the middle tower is significantly higher than other components,and the bridge failure starts from the middle tower,exhibiting a characteristic of local failure.For FS and PEDS,the fragility of the edge tower is higher than the middle tower.The system fragility of RS is higher than FS and PEDS.Taking the failure of dampers into account is necessary to obtain reliable seismic capacity of cable-stayed bridges.展开更多
Rigid barrier deflectors can effectively prevent overspilling landslides,and can satisfy disaster prevention requirements.However,the mechanisms of interaction between natural granular flow and rigid barrier deflector...Rigid barrier deflectors can effectively prevent overspilling landslides,and can satisfy disaster prevention requirements.However,the mechanisms of interaction between natural granular flow and rigid barrier deflectors require further investigation.To date,few studies have investigated the impact of deflectors on controlling viscous debris flows for geological disaster prevention.To investigate the effect of rigid barrier deflectors on impact mechanisms,a numerical model using the smoothed particle hydrodynamics(SPH)method with the Herschel–Bulkley model is proposed to simulate the interaction between natural viscous flow and single/dual barriers with and without deflectors.This model was validated using laboratory flume test data from the literature.Then,the model was used to investigate the influence of the deflector angle and multi-barrier arrangements.The optimal configuration of multi-barriers was analyzed with consideration to the barrier height and distance between the barriers,because these metrics have a significant impact on the viscous flow pile-up,run-up,and overflow mechanisms.The investigation considered the energy dissipation process,retention efficiency,and dead-zone formation.Compared with bare barriers with similar geometric characteristics and spatial distribution,rigid barriers with deflectors exhibit superior effectiveness in preventing the overflow and overspilling of viscous debris flow.Recommendations for the rational design of deflectors and the optimal arrangement of multi-barriers are provided to mitigate geological disasters.展开更多
基金supported by the National Natural Science Foundation of China(22078009)National Key Research Program of China(2021YFC3001102,2021YFC3001100).
文摘Millimeter channel reactors(MCRs)have received increasing attention because of their ability to enhance treatment capacity in addition to the advantages of microchannels.In previous studies,less work has been conducted on the micromixing process and enhancement strategies for non-Newtonian fluids in MCRs.In this study,the micromixing efficiency in MCRs was experimentally investigated using CMC(carboxymethyl cellulose sodium)aqueous solution to simulate a non-Newtonian fluid,and the enhanced mechanism of micromixing efficiency by the addition of internals and rotation was analyzed by computational fluid dynamics(CFD)simulations.The results show that in the conventional channel,increasing the flow rate improves the micromixing efficiency when the CMC concentration is low.However,when the CMC concentration is higher,the higher the flow rate,the lower the micromixing efficiency.The highest micromixing efficiency is obtained for the rotationally coupled inner components,followed by the single rotation and the lowest is for the internals only.CFD simulations reveal that the most effective way to improve the micromixing efficiency of non-Newtonian fluids with shear-thinning behavior is to increase the shear force in the reactor,which effectively reduces the apparent viscosity.These results provide the theoretical foundation for enhancing the micromixing process of non-Newtonian fluids in small-size reactors.
基金supports for this project from State Key Laboratory of Chemical Safety(SKLCS–2024001)are gratefully acknowledged。
文摘Bubble breakup at T-junction microchannels is the basis for the numbering-up of gas−liquid two-phase flow in parallelized microchannels. This article presents the bubble breakup in viscous liquids at a microfluidic T-junction. Nitrogen is used as the gas phase, and glycerol-water mixtures with different mass concentration of glycerol as the liquid phase. The evolution of the gas−liquid interface during bubble breakup at the microfluidic T-junction is explored. The thinning of the bubble neck includes the squeezing stage and the rapid pinch-off stage. In the squeezing stage, the power law relation is found between the minimum width of the bubble neck and the time, and the values of exponents α1 and α2 are influenced by the viscous force. The values of pre-factors m_(1) and m_(2) are negatively correlated with the capillary number. In the rapid pinch-off stage, the thinning of the bubble neck is predominated by the surface tension, and the minimum width of the bubble neck can be scaled with the remaining time as power-law. The propagation of the bubble tip can be characterized by the power law between the movement distance and the time, with decreasing exponent as increased liquid viscosity.
文摘Viscoelastic nanofluid flow has drawn substantial interest due to its industrial uses,including research and testing of medical devices,lubrication and tribology,drug delivery systems,and environmental remediation.This work studies nanofluid flow over a viscoelastic boundary layer,focusing on mass and heat transmission.An analysis is performed on the flow traversing a porous sheet undergoing nonlinear stretching.It assesses the consequences of viscous dissipation and thermal radiation.The scientific nanofluid framework laid out by Buongiorno has been exploited.The partial differential equations illustrating the phenomena can be transfigured into ordinary differential equations by utilizing appropriate similarity transformations.The simplified equations are unmasked using the Homotopy Analysis Method(HAM),a semi-analytical approach designed to solve nonlinear ordinary and partial differential equations commonly encountered in numerous scientific and engineering disciplines.Calculations are executed to ascertain the numerical solutions related to temperature,concentration,and velocity fields,accompanied by the skin friction coefficient,local Nusselt number,and local Sherwood number.Visualizations of the results are accompanied by pertinent explanations grounded in scientific principles.The temperature distribution and corresponding thermal layer have been enhanced due to radiative and viscous dissipation characteristics.Additionally,it has been noted that a delay in fluid movement results from an improvement in the porous medium parameter and magnetic field values.A falling trend in the Nusselt number is observed as the Eckert and thermophoresis parameters increase.The current numerical results have been effectively validated against previous difficulties.
基金funded by National Natural Science Foundation of China(Grant No.11872372)Graduate Innovation Foundation of Hunan Province of China(Grant No.CX20230018).
文摘Viscoelastic solids,such as composite propellants,exhibit significant time and rate dependencies,and their fracture processes display high levels of nonlinearity.However,the correlation between crack propagation and viscoelastic energy dissipation in these materials remains unclear.Therefore,accurately modeling and understanding of their fracture behavior is crucial for relevant engineering applications.This study proposes a novel viscoelastic phase-field model.In the numerical implementation,the adopted adaptive time-stepping iterative strategy effectively accelerates the coupling iteration efficiency between the phase-field and the displacement field.Moreover,all unknown parameters in the model,including the form of the phase-field degradation function,are identified through fitting against experimental data.Based on an introduced scaling factor,themechanical response behaviors of solid propellant dogbone specimens under cyclic loading,relaxation,and tension are analyzed,and the predictive capacity of the model is demonstrated by comparing the experimental data with the simulation results.Finally,modeling results for Mode-I and Mode-II crack propagation in single-edge-notched specimens indicate that the reduction of viscous energy dissipation will significantly increase the fracture growth rate,but under the same boundary conditions,the crack path remains unchanged.
基金supported by the National Natural Science Foundation of China(Grant No.42202316)the China Postdoctoral Science Foundation(Grant No.2022M712963)the Open Fund of Badong National Observation and Research Station of Geohazards(Grant No.BNORSG-202309).
文摘Non-Darcian flow in rock fractures exhibits significant anisotropic characteristics,which can be affected by mechanical processes,such as cyclic shearing.Understanding the evolution of anisotropic nonDarcian flow is crucial for characterizing groundwater flow and mass/heat transport in fractured rock masses.In this study,we conducted experiments on non-Darcian flow in single rough fractures under cyclic shearing conditions,aiming to analyze the anisotropic evolution of inertial permeability and viscous permeability.We established quantitative characterization models for the two types of permeability.First,we conducted cyclic shearing experiments on four sets of 24 rough rock fractures,investigating their shear characteristics.Then,we performed 480 non-Darcian flow experiments to analyze the anisotropic evolution of viscous permeability and inertial permeability of these rock fractures.The results showed that viscous permeability exhibited significant differences only in the orthogonal direction,while inertial permeability exhibited differences in both orthogonal and opposite directions.With increase in the shear cycles,the differences in the orthogonal direction gradually increased,while those in opposite direction gradually decreased.Finally,we established characterization equations for the two permeabilities based on the proposed directional geometric parameters and validated the performance of these equations with experimental data.These findings are useful for the quantitative characterization of the evolution of non-Darcian flow in fractures under dynamic loading conditions.
文摘Maximizing the efficiency of thermal engineering equipment involves minimizing entropy generation,which arises from irreversible processes.This study examines thermal transport and entropy generation in viscous flow over a radially stretching disk,incorporating the effects of magnetohydrodynamics(MHD),viscous dissipation,Joule heating,and radiation.Similarity transformations are used to obtain dimensionless nonlinear ordinary differential equations(ODEs)from the governing coupled partial differential equations(PDEs).The converted equations are then solved by using the BVP4C solver in MATLAB.To validate the findings,the results are compared with previously published studies under fixed parameter conditions,demonstrating strong agreement.Various key parameters are analyzed graphically to assess their impact on velocity and temperature distributions.Additionally,Bejan number and entropy generation variations are presented for different physical parameters.The injection parameter(S<0)increases the heat transfer rate,while the suction parameter(S>0)reduces it,exhibiting similar effects on fluid velocity.The magnetic parameter(M)effectively decreases entropy generation within the range of approximately 0≤η≤0.6.Beyond this interval,its influence diminishes as entropy generation values converge,with similar trends observed for the Bejan number.Furthermore,increased thermal radiation intensity is identified as a critical factor in enhancing entropy generation and the Bejan number.
文摘Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady heat and mass transport properties.The hybrid nanofluid’s enhanced heat transfer efficiency is a major benefit in high-performance engineering applications.It is composed of two separate nanoparticles suspended in a base fluid and is chosen for its improved thermal properties.Thermal radiation,chemical reactions,a transverse magnetic field,surface stretching with time,injection or suction through the porous medium,and the effect of inclination,which introduces gravity-induced buoyancy forces,are all important physical phenomena that are taken into account in the analysis.A system of nonlinear ordinary differential equations(ODEs)is derived from the governing partial differential equations for mass,momentum,and energy by applying suitable similarity transformations.This simplifies the modeling procedure.The bvp4c solver in MATLAB is then used to numerically solve these equations.Different governing parameters modify temperature,concentration,and velocity profiles in graphs and tables.These factors include radiation intensity,chemical reaction rate,magnetic field strength,unsteadiness,suction/injection velocity,inclination angle,and nanoparticle concentration.A complex relationship between buoyancy and magnetic factors makes hybrid nanofluids better at heat transmission than regular ones.Thermal systems including cooling technologies,thermal coatings,and electronic heat management benefit from these findings.
基金financially supported by the Key Research and Development Program of Hubei Province(Nos.2022BCA077 and 2022BCA082).
文摘Styrene-butadiene-styrene(SBS)modified asphalt(SA)has long found effective applications in road construction materials.When combined with fillers,SBS-modified asphalt has demonstrated promising resistance to fatigue cracking caused by temperature fluctuations and aging.In this study,molybdenum disulfide(MoS_(2))and polyphosphoric acid(PPA)were ground in naphthenic oil(NO)and subjected to mechanical activation to create PPAmodified MoS_(2),referred to as OMS-PPA.By blending various ratios of OMS-PPA with SBS-modified asphalt,composite-modified asphalts were successfully developed to enhance their overall properties.To assess the mechanical characteristics and stability of these modified asphalts,various methods were employed,including penetration factor,flow activation energy,fluorescence microscopy,and dynamic shear rheology.Additionally,the short-term aging performance was evaluated using Fourier transform infrared(FTIR)spectroscopy and nanoindentation tests.The results revealed a 3.7%decrease in the penetration-temperature coefficient for SAOMS compared to SA,while 1-SA-OMS-PPA showed an even greater reduction of 7.1%.Furthermore,after short-term aging,carboxyl group generation in SA increased by 5.93%,while SA-OMS exhibited a smaller rise of 1.36%,and 1-SA-OMS-PPA saw an increase of just 0.93%.The study also highlighted significant improvements in the hardness of these materials.The hardness change ratio for SA-OMS decreased by 43.08%,while the ratio for 1-SA-OMS-PPA saw a notable reduction of 65.16% compared to unmodified SA.These findings suggest that OMS-PPA contributed to improvements in temperature sensitivity,particle dispersibility,and resistance to shortterm aging in asphalts.The results hold significant promise for the future development of advanced asphalt-based materials with potential high-value applications in flexible pavements for highways.
文摘This study rigorously examines the interplay between viscous dissipation,magnetic effects,and thermal radiation on the flow behavior of a non-Newtonian Carreau squeezed fluid passing by a sensor surface within a micro cantilever channel,aiming to deepen our understanding of heat transport processes in complex fluid dynamics scenarios.The primary objective is to elucidate how physical operational parameters influence both the velocity of fluid flow and its temperature distribution,utilizing a comprehensive numerical approach.Employing a combination of mathematical modeling techniques,including similarity transformation,this investigation transforms complex partial differential equations into more manageable ordinary ones,subsequently solving them using the homotopy perturbation method.By analyzing the obtained solutions and presenting them graphically,alongside detailed analysis,the study sheds light on the pivotal role of significant parameters in shaping fluid movement and energy distribution.Noteworthy observations reveal a substantial increase in fluid velocity with escalating magnetic parameters,while conversely,a contrasting trend emerges in the temperature distribution,highlighting the intricate relationship between magnetic effects,flow dynamics,and thermal behavior in non-Newtonian fluids.Further,the suction velocity enhance both the local skin friction and Nusselt numbers,whereas theWeissenberg number reduces them,opposite to the effect of the power-law index.
文摘This paper investigates the mechanisms of rock failure related to axial splitting and shear failure due to hoop stresses in cylindrical specimens.The hoop stresses are caused by normal viscous stress.The rheological dynamics theory(RDT)is used,with the mechanical parameters being determined by P-and S-wave velocities.The angle of internal friction is determined by the ratio of Young's modulus and the dynamic modulus,while dynamic viscosity defines cohesion and normal viscous stress.The effect of frequency on cohesion is considered.The initial stress state is defined by the minimum cohesion at the elastic limit when axial splitting can occur.However,as radial cracks grow,the stress state becomes oblique and moves towards the shear plane.The maximum and nonlinear cohesions are defined by the rock parameters under compressive strength when the radial crack depth reaches a critical value.The efficacy and precision of RDT are validated through the presentation of ultrasonic measurements on sandstone and rock specimens sourced from the literature.The results presented in dimensionless diagrams can be utilized in microcrack zones in the absence of lateral pressure in rock masses that have undergone disintegration due to excavation.
基金supported by the National Key Research and Development Program of China(No.2022YFB3706704)the Academician Special Science Research Project of CCCC(No.YSZX-03-2022-01-B).
文摘To investigate the influence of different longitudinal constraint systems on the longitudinal displacement at the girder ends of a three-tower suspension bridge,this study takes the Cangrong Xunjiang Bridge as an engineering case for finite element analysis.This bridge employs an unprecedented tower-girder constraintmethod,with all vertical supports placed at the transition piers at both ends.This paper aims to study the characteristics of longitudinal displacement control at the girder ends under this novel structure,relying on finite element(FE)analysis.Initially,based on the Weigh In Motion(WIM)data,a random vehicle load model is generated and applied to the finite elementmodel.Several longitudinal constraint systems are proposed,and their effects on the structural response of the bridge are compared.The most reasonable system,balancing girder-end displacement and transitional pier stress,is selected.Subsequently,the study examines the impact of different viscous damper parameters on key structural response indicators,including cumulative longitudinal displacement at the girder ends,maximum longitudinal displacement at the girder ends,cumulative longitudinal displacement at the pier tops,maximum longitudinal displacement at the pier tops,longitudinal acceleration at the pier tops,and maximum bending moment at the pier bottoms.Finally,the coefficient of variation(CV)-TOPSIS method is used to optimize the viscous damper parameters for multiple objectives.The results show that adding viscous dampers at the side towers,in addition to the existing longitudinal limit bearings at the central tower,can most effectively reduce the response of structural indicators.The changes in these indicators are not entirely consistent with variations in damping coefficient and velocity exponent.The damper parameters significantly influence cumulative longitudinal displacement at the girder ends,cumulative longitudinal displacement at the pier tops,and maximum bending moments at the pier bottoms.The optimal damper parameters are found to be a damping coefficient of 5000 kN/(m/s)0.2 and a velocity exponent of 0.2.
基金supported by the Research and Innovation Fund for Graduate Students of Southwest Petroleum University(No.2022KYCX027)supported by the National Natural Science Foundation for Youth Grant(No.41902157).
文摘Studying immiscible fluid displacement patterns can provide a better understanding of displacement processes within heterogeneous porous media,thereby helping improving oil recovery and optimizing geological CO_(2) sequestration.As the injection rate of water displacing oil increases and the displacement pattern transits from capillary fingering to viscous fingering,there is a broad crossover zone between the two that can adversely affect the oil displacement efficiency.While previous studies have utilized phase diagrams to investigate the influence of the viscosity ratio and wettability of the crossover zone,fewer have studied the impact of rock heterogeneity.In this study,we created pore network models with varying degrees of heterogeneity to simulate water flooding at different injection rates.Our model quantifies capillary and viscous fingering characteristics while investigating porous media heterogeneity's role in the crossover zone.Analysis of simulation results reveals that a higher characteristic front flow rate within the crossover zone leads to earlier breakthrough and reduced displacement efficiency.Increased heterogeneity in the porous media raises injection-site pressure,lowers water saturation,and elevates the characteristic front flow rate,thereby expanding the extent of crossover zone.
文摘This study explores free convective heat transfer in an electrically conducting nanofluid flow over a moving semi-infinite flat plate under the influence of an induced magnetic field and viscous dissipation.The velocity and magnetic field vectors are aligned at a distance from the plate.The Spectral Relaxation Method(SRM)is used to numerically solve the coupled nonlinear partial differential equations,analyzing the effects of the Eckert number on heat and mass transfer.Various nanofluids containing Cu,Ag,Al_(2)O_(3),and TiO_(2) nanoparticles are examined to assess how external magnetic fields influence fluid behavior.Key parameters,including the nanoparticle volume fraction ϕ,magnetic parameter M,magnetic Prandtl number Prm,and Eckert number Ec,are evaluated for their impact on velocity,induced magnetic field,and heat transfer.Results indicate that increasing the magnetic parameter reduces velocity and magnetic field components in alumina-water nanofluids,while a higher nanoparticle volume fraction enhances the thermal boundary layer.Greater viscous dissipation(Ec)increases temperature,and Al_(2)O_(3) nanofluids exhibit higher speeds than Cu,Ag,and TiO_(2) due to density differences.Silver-water nanofluids,with their higher density,move more slowly.The SRM results closely align with those from Maple,confirming the method’s accuracy.
基金supported by JUST Start-up Fund for Science Research,the Jiangsu Natural Science Foundation(Grant No.BK20210885).
文摘The internal solitary wave(ISW)represents a frequent and severe oceanic dynamic phenomenon observed in the South China Sea,exposing marine structures to sudden loads.This paper examines the prediction model of interaction loads between ISW and FPSO,accounting for varying attack angles and incorporating ISW theories.The research demonstrates that the horizontal and transverse forces on FPSO under internal solitary waves(ISWs)comprise wave pressure difference force and viscous force,while the vertical force primarily consists of vertical wave pressure difference force.The wave pressure difference force is determined using the Froude-Krylov equation.The viscous force is derived from the tangential particle velocity induced by ISW and the viscous coefficient.The viscous coefficient formula is obtained through regression analysis of experimental data with different ISW attack angles.The research reveals that the horizontal viscous coefficient C_(vx)decreases as Reynolds number(R_(e))increases,while the transverse viscous coefficient C_(vy)initially increases and subsequently decreases with the growth of the Keulegan-Carpenter number(KC).Moreover,changes in wave propagation direction significantly affect the extreme magnitudes of both horizontal and transverse forces,and simultaneously modify the transverse force orientation,while having minimal impact on the vertical force.Additionally,the forces increase with the ISW’s amplitude.For horizontal and transverse forces,a thinner upper fluid layer generates larger forces.Comparative analysis of experimental,numerical,and theoretical results indicates strong agreement between theoretical predictions and experimental and numerical outcomes.
基金supported by the National Key Research and Development Program of China(2019YFA0705800)the National Natural Science Foundation of China(52030001)the Science&Technology Commission of Shanghai Municipality(20dz1207600).
文摘Drying operations are of grave importance to realize the reduction and utilization of sewage sludge resources,but the conventional thermal evaporation drying(TED)technology presents challenges due to the need for a large amount of thermal energy to conquer the phase-change latent heat of moisture.Herein,we report a non-phase change technology based on particle high-speed self-rotation in a cyclone for fast,low-temperature drying of viscous sludge with high-moisture contents.Dispersed phase medium(DPM)is introduced into the cyclone self-rotation drying(CSRD)reactor to enhance the dispersion of the viscous sludge.The effects of carrier gas temperature,feeding rate,size,and proportion of DPM particles in the drying process are systematically examined.Under optimal operating conditions,the weighted content of moisture in the viscous sludge could be reduced from 80%to 15.01%in less than 5 s,achieving a high drying efficiency of 95.79%.Theoretical calculations also reveal that 89.26%of the moisture is removed through non-phase change pathway,contributing to a 522-fold increase in the drying rate of CSRD compared to TED technology.This investigation presents a sustainable effective approach for high moisture viscous sludge treatment with low energy consumption and carbon emissions.
基金Project(52276068)supported by the National Natural Science Foundation of China。
文摘This study examines the intricate occurrences of thermal and solutal Marangoni convection in three-layered flows of viscous fluids,with a particular emphasis on their relevance to renewable energy systems.This research examines the flow of a three-layered viscous fluid,considering the combined influence of heat and solutal buoyancy driven Rayleigh-Bénard convection,as well as thermal and solutal Marangoni convection.The homotopy perturbation method is used to examine and simulate complex fluid flow and transport phenomena,providing important understanding of the fundamental physics and assisting in the optimization of various battery configurations.The inquiry examines the primary elements that influence Marangoni convection and its impact on battery performance,providing insights on possible enhancements in energy storage devices.The findings indicate that the velocity profiles shown graphically exhibit a prominent core zone characterized by the maximum speed,which progressively decreases as it approaches the walls of the channel.This study enhances our comprehension of fluid dynamics and the transmission of heat and mass in intricate systems,which has substantial ramifications for the advancement of sustainable energy solutions.
基金supported by the NSFC(12271122)the Fundamental Research Funds for the Central Universities.Han’s research was supported by the Fundamental Research Funds for the Central Universities(3072023GIP2401).
文摘In this paper,we consider the initial boundary value problem for the 2-D hyperbolic viscous Cahn-Hilliard equation.Firstly,we prove the existence and uniqueness of the local solution by the Galerkin method and contraction mapping principle.Then,using the potential well theory,we study the global well-posedness of the solution with initial data at different levels of initial energy,i.e.,subcritical initial energy,critical initial energy and arbitrary positive initial energy.For subcritical initial energy,we prove the global existence,asymptotic behavior and finite time blowup of the solution.Moreover,we extend these results to the critical initial energy using the scaling technique.For arbitrary positive initial energy,including the sup-critical initial energy,we obtain the sufficient conditions for finite time blow-up of the solution.As a further study for estimating the blowup time,we give a unified expression of the lower bound of blowup time for all three initial energy levels and estimate the upper bound of blowup time for subcritical and critical initial energy.
文摘The high thermal conductivity of the nanoparticles in hybrid nanofluids results in enhanced thermal conductivity associated with their base fluids.Enhanced heat transfer is a result of this high thermal conductivity,which has significant applications in heat exchangers and engineering devices.To optimize heat transfer,a liquid film of Cu and TiO_(2)hybrid nanofluid behind a stretching sheet in a variable porous medium is being considered due to its importance.The nature of the fluid is considered time-dependent and the thickness of the liquid film is measured variable adjustable with the variable porous space and favorable for the uniform flow of the liquid film.The solution of the problem is acquired using the homotopy analysis method HAM,and the artificial neural network ANN is applied to obtain detailed information in the form of error estimation and validations using the fitting curve analysis.HAM data is utilized to train the ANN in this study,which uses Cu and TiO_(2)hybrid nanofluids in a variable porous space for unsteady thin film flow,and it is used to train the ANN.The results indicate that Cu and TiO_(2)play a greater role in boosting the rate.
基金National Key R&D Program of China under Grant No.2022YFC3003603。
文摘Seismic fragility analysis of three-tower cable-stayed bridges with three different structural systems,including rigid system(RS),floating system(FS),and passive energy dissipation system(PEDS),is conducted to study the effects of connection configurations on seismic responses and fragilities.Finite element models of bridges are established using OpenSees.A new ground motion screening method based on the statistical characteristic of the predominant period is proposed to avoid irregular behavior in the selection process of ground motions,and incremental dynamic analysis(IDA)is performed to develop components and systems fragility curves.The effects of damper failure on calculated results for PEDS are examined in terms of seismic response and fragility analysis.The results show that the bridge tower is the most affected component by different structural systems.For RS,the fragility of the middle tower is significantly higher than other components,and the bridge failure starts from the middle tower,exhibiting a characteristic of local failure.For FS and PEDS,the fragility of the edge tower is higher than the middle tower.The system fragility of RS is higher than FS and PEDS.Taking the failure of dampers into account is necessary to obtain reliable seismic capacity of cable-stayed bridges.
基金supported by the National Natural Science Foundation of China(Grant Nos.42120104008 and 42207198).
文摘Rigid barrier deflectors can effectively prevent overspilling landslides,and can satisfy disaster prevention requirements.However,the mechanisms of interaction between natural granular flow and rigid barrier deflectors require further investigation.To date,few studies have investigated the impact of deflectors on controlling viscous debris flows for geological disaster prevention.To investigate the effect of rigid barrier deflectors on impact mechanisms,a numerical model using the smoothed particle hydrodynamics(SPH)method with the Herschel–Bulkley model is proposed to simulate the interaction between natural viscous flow and single/dual barriers with and without deflectors.This model was validated using laboratory flume test data from the literature.Then,the model was used to investigate the influence of the deflector angle and multi-barrier arrangements.The optimal configuration of multi-barriers was analyzed with consideration to the barrier height and distance between the barriers,because these metrics have a significant impact on the viscous flow pile-up,run-up,and overflow mechanisms.The investigation considered the energy dissipation process,retention efficiency,and dead-zone formation.Compared with bare barriers with similar geometric characteristics and spatial distribution,rigid barriers with deflectors exhibit superior effectiveness in preventing the overflow and overspilling of viscous debris flow.Recommendations for the rational design of deflectors and the optimal arrangement of multi-barriers are provided to mitigate geological disasters.
