In this investigation,a hybrid approach integrating the IDDES turbulence model and FW-H is employed to forecast the hydroacoustic of the rim driven thruster(RDT)under non-cavitation and uniform flow conditions at vary...In this investigation,a hybrid approach integrating the IDDES turbulence model and FW-H is employed to forecast the hydroacoustic of the rim driven thruster(RDT)under non-cavitation and uniform flow conditions at varying loading conditions(J=0.3 and J=0.6).It is revealed that the quadrupole term contribution in the P-FWH method significantly affects the monopole term in the low-frequency region,while it mainly affects the dipole term in the high-frequency region.Specifically,the overall sound pressure levels(SPL)of the RDT using the P-FWH method are 2.27 dB,10.03 dB,and 16.73 dB at the receiving points from R1 to R3 under the heavy-loaded condition,while they increase by 0.67 dB at R1,and decrease by 14.93 dB at R2,and 22.20 dB at R3,for the light-loaded condition.The study also utilizes the pressure-time derivatives to visualize the numerical noise and to pinpoint the dynamics of the vortex cores,and the optimization of the grid design can significantly reduce the numerical noise.The computational accuracy of the P-FWH method can meet the noise requirements for the preliminary design of rim driven thrusters.展开更多
The issue of resistance reduction through hull ventilation is of particular interest in contemporary research.This paper presents multiphase computational fluid dynamics(CFD)simulations with 2-DOF motion of a planing ...The issue of resistance reduction through hull ventilation is of particular interest in contemporary research.This paper presents multiphase computational fluid dynamics(CFD)simulations with 2-DOF motion of a planing hull.The original hull was modified by introducing a step to allow air ventilation.Following an assessment of the hull performance,a simulation campaign in calm water was conducted to characterize the hull at various forward speeds and air insufflation rates for a defined single step geometry.Geometric analysis of the air layer thickness beneath the hull for each simulated condition was performed using a novel method for visualizing local air thickness.Additionally,two new parameters were introduced to understand the influence of spray rails on the air volume beneath the hull and to indicate the primary direction of ventilated air escape.A validation campaign and an assessment of uncertainty of the simulation has been conducted.The features offered by the CFD methodology include the evaluation of the air layer thickness as a function of hull velocity and injection flow rate and the air volume distribution beneath the hull.The air injection velocity can be adjusted across various operating conditions,thereby preventing performance or efficiency loss during navigation.Based on these findings,the study highlights the benefits of air insufflation in reducing hull resistance for high-speed planing vessels.This work lays a robust foundation for future research and new promising topics,as the exploration of air insufflation continues to be a topic of contemporary interest within naval architecture and hydrodynamics.展开更多
The present study focuses on the flow of a yield-stress(Bingham)nanofluid,consisting of suspended Fe3O4 nanoparticles,subjected to a magnetic field in a backward-facing step duct(BFS)configuration.The duct is equipped...The present study focuses on the flow of a yield-stress(Bingham)nanofluid,consisting of suspended Fe3O4 nanoparticles,subjected to a magnetic field in a backward-facing step duct(BFS)configuration.The duct is equipped with a cylindrical obstacle,where the lower wall is kept at a constant temperature.The yield-stress nanofluid enters this duct at a cold temperature with fully developed velocity.The aim of the present investigation is to explore the influence of flow velocity(Re=10 to 200),nanoparticle concentration(ϕ=0 to 0.1),magnetic field intensity(Ha=0 to 100),and its inclination angle(γ=0 to 90)and nanofluid yield stress(Bn=0 to 20)on the thermal and hydrodynamic efficiency inside the backward-facing step.The numerical results have been obtained by resolving the momentum and energy balance equations using the Galerkin finite element method.The obtained results have indicated that an increase in Reynolds number and nanoparticle volume fraction enhances heat transfer.In contrast,a significant reduction is observed with an increase in Hartmann and Bingham numbers,resulting in quasi-immobilization of the fluid under the magnetic influence and radical solidification of this type of fluid,accompanied by the suppression of the vortex zone downstream of the cylindrical obstacle.This study sheds light on the complexity of this magnetically influenced fluid,with potential implications in various engineering and materials science fields.展开更多
Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures worldwide.An understanding of the liquefaction triggering,and the post-failure large deformation behaviour is es...Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures worldwide.An understanding of the liquefaction triggering,and the post-failure large deformation behaviour is essential for designing resilient infrastructure.The present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of geotechnical structures.The coupled flowdeformation behaviour of soils subjected to cyclic loading is described using the PM4Sand model implemented in a three-phase,single-layer SPH framework.A staggered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energy modes and tensile instability.Further,non-reflecting boundary conditions for seismic analysis of semi-infinite soil domains using the SPH method are proposed.The numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level ground site,and liquefaction-induced failure of the Lower San Fernando Dam.Satisfactory agreement for liquefaction triggering and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading on field-scale geotechnical structures.The present study also serves as the basis for future advancements of the SPH method for applications related to earthquake geotechnical engineering.展开更多
In this work,we present a parallel implementation of radiation hydrodynamics coupled with particle transport,utilizing software infrastructure JASMIN(J Adaptive Structured Meshes applications INfrastructure)which enca...In this work,we present a parallel implementation of radiation hydrodynamics coupled with particle transport,utilizing software infrastructure JASMIN(J Adaptive Structured Meshes applications INfrastructure)which encapsulates high-performance technology for the numerical simulation of complex applications.Two serial codes,radiation hydrodynamics RH2D and particle transport Sn2D,have been integrated into RHSn2D on JASMIN infrastructure,which can efficiently use thousands of processors to simulate the complex multi-physics phenomena.Moreover,the non-conforming processors strategy has ensured RHSn2D against the serious load imbalance between radiation hydrodynamics and particle transport for large scale parallel simulations.Numerical results show that RHSn2D achieves a parallel efficiency of 17.1%using 90720 cells on 8192 processors compared with 256 processors in the same problem.展开更多
We present and explore a new shock-capturing particle hydrodynamics approach.Our starting point is a commonly used discretization of smoothed particle hydrodynamics.We enhance this discretization with Roe’s approx-im...We present and explore a new shock-capturing particle hydrodynamics approach.Our starting point is a commonly used discretization of smoothed particle hydrodynamics.We enhance this discretization with Roe’s approx-imate Riemann solver,we identify its dissipative terms,and in these terms,we use slope-limited linear reconstruction.All gradients needed for our method are calculated with linearly reproducing kernels that are constructed to enforce the two lowest-order consistency relations.We scrutinize our reproducing kernel implementation carefully on a“glass-like”particle distribution,and we find that constant and linear functions are recovered to machine precision.We probe our method in a series of challenging 3D benchmark problems ranging from shocks over instabilities to Schulz-Rinne-type vorticity-creating shocks.All of our simulations show excellent agreement with analytic/reference solutions.展开更多
Fish swimming hydrodynamics serves as a critical foundation for aquatic ecological conservation,with recent research extending from 2D to 3D perspectives.This study employs 3D high-fidelity modeling with dynamic mesh ...Fish swimming hydrodynamics serves as a critical foundation for aquatic ecological conservation,with recent research extending from 2D to 3D perspectives.This study employs 3D high-fidelity modeling with dynamic mesh technology to investigate how cylindrical obstacles at varying positions affect Carassius auratus locomotion.Analysis of nine configurations reveals bidirectional flow interactions between fish and cylinders,with cylinder wake influence persisting at 1-2 times the total length intervals but diminishing at 3times.Compared with swimming in uniform flow,the mechanical benefit of C.auratus located 2 times the total length directly behind the cylinder is the largest,and its value reaches 4.19 times.Wavelet analysis of 30-cycle mechanical data demonstrates closer intervals enhance benefit magnitude,whereas greater distances accelerate benefit realization.These 3D computational findings corroborate 2D studies while providing new spatial interaction insights,offering theoretical foundations for fish conservation strategies related to hydraulic structures.展开更多
A comprehensive understanding of surface wetting phenomena in microchannels is essential for optimizing particle transport and filtration processes.This study numerically investigates the dynamics of a freely suspende...A comprehensive understanding of surface wetting phenomena in microchannels is essential for optimizing particle transport and filtration processes.This study numerically investigates the dynamics of a freely suspended elliptical cylinder in confined Poiseuille flow,with a focus on Navier slip boundary conditions.The smoothed particle hydrodynamics method is employed,which is advantageous for its Lagrangian framework in handling dynamic fluid-solid interfaces with slip.Our results demonstrate that the slip conditions enable precise control over inertial focusing positions and particle motion modes.Compared to no-slip scenarios,unilateral wall slip induces two novel motion types:“leaning”and“rolling”.When equal slip lengths are applied to both walls,even small slip values facilitate off-center inertial focusing and elevate equilibrium positions.Slip on the cylinder surface further enhances inertial lift while suppressing rotational dynamics.In particular,under strong confinement or with large particle-surface slip lengths,we identify an additional distinct motion regime termed“inclined.”These findings provide new insights for active particle manipulation in microfluidic applications.展开更多
This study aims to enhance the maneuvering advantages of the waterjet unit through parametric design,performance evaluation,and optimization of the one-piece waterjet propulsion steering and reversing gear(SRG).The SR...This study aims to enhance the maneuvering advantages of the waterjet unit through parametric design,performance evaluation,and optimization of the one-piece waterjet propulsion steering and reversing gear(SRG).The SRG’s performance evaluation stems mainly from the effect of the free surface,the varying sailing speeds of the ship,and its performance while functioning at the stern of the waterjet-propelled vessel.Parameters such as the length,width,and height of the steering gear,as well as the inclination,width,and curvature of the reversing gear,significantly influence the SRG.Although the free surface has a great impact on the force of the SRG,its performance trend remains unaffected.When the SRG operates at the stern of the ship,the optimized scheme’s lateral force improves by an average of 8.08%for sailing with a rudder angle condition and an average of 45.69%for reversing sailing with a rudder angle condition.The longitudinal force of the optimized scheme improves by more than 23%when sailing without a rudder angle condition and by an average of 31.75%when sailing with a reversed rudder angle condition.Additionally,the speed of the rotor has a minimal effect on the lateral force and a significant effect on the longitudinal force.展开更多
The interaction between extreme waves and structures is a crucial study area in marine science,as it significantly influences safety and disaster prevention strategies for marine and coastal engineering.To investigate...The interaction between extreme waves and structures is a crucial study area in marine science,as it significantly influences safety and disaster prevention strategies for marine and coastal engineering.To investigate the flow field of a semi-submersible against extreme waves,a model simulating solitary wave interactions with the semi-submersible system was developed via the meshless smoothed particle hydrodynamics(SPH)method and Rayleigh’s theory.Notably,the wave surface and wave load results obtained from the SPH model,compared with those of OpenFOAM,result in an interaction test case between solitary waves and partially submerged rectangular obstacles and show good agreement,with a maximum relative error of 3.4%.An analysis of the calculated results of the semi-submersible facing solitary waves revealed several key findings:overtopping,which decreases with increasing water depth,occurs on the structure when the non-submerged ratio is 0.33 and the wave height surpasses 0.2 m.The transmission coefficient decreases with increasing wave height but increases as the water depth increases.Furthermore,the reflection coefficient peaks at a wave height H0=0.2 m.The dissipation coefficient displays a valley trend with a small water depth,whereas it increases monotonically with increasing water depth.The dissipation coefficient decreases with increasing water depth.展开更多
Shallow water infrastructure needs to support increased activity on the shores of Semarang.This study chooses several pontoons because of their good stability,rolling motion,and more expansive space.A coupled simulati...Shallow water infrastructure needs to support increased activity on the shores of Semarang.This study chooses several pontoons because of their good stability,rolling motion,and more expansive space.A coupled simulation method consisting of hydrodynamic and structural calculations has been used to evaluate a catamaran pontoon’s motion and structural integrity.Four different space sizes are set for the pontoon system:5 m,5.5 m,6 m,and 6.5 m.The frequency domain shows that the pontoon space affects the RAO in wave periods ranging from 3 s to 5 s.At wave periods of 3 s,4 s,and 5 s,the pontoon space significantly affects the maximum motion and chain tension parameter values,which are evaluated via time domain simulation.The critical stress of the pontoon is shown at a wave period of 5 s for 5 m and 5.5 m of pontoon space,which shows that the stress can reach 248 MPa.展开更多
In the Maradi region,the alluvial aquifer of the Goulbi’N Maradi rests on the aquifers of the Continental Hamadien.It represents an essential reserve for irrigation and drinking water supply.However,due to its high d...In the Maradi region,the alluvial aquifer of the Goulbi’N Maradi rests on the aquifers of the Continental Hamadien.It represents an essential reserve for irrigation and drinking water supply.However,due to its high demand and the excessive use of chemical fertilizers and pesticides in irrigation,a ten-year analysis of the dynamics of this alluvial aquifer has proven necessary.Hence,this study,based on hydrodynamic and hydrochemical approaches,aims to improve knowledge of the dynamics of the alluvial aquifer from 2015 to 2023.The novelty of this study lies in its comprehensive coverage of the entire Goulbi N’Maradi valley in Niger,employing a multidimensional approach.The data used were composed of water samples taken from forty-five structures,piezometric monitoring sheets,and digital terrain models.The results reveal that the Goulbi’N Maradi aquifer exhibits continuous piezometry,characterized by a general flow pattern from south to northwest and a relatively strong hydraulic gradient in the southern part,indicating recharge from recent infiltration of rain and floodwaters.The water balances calculated at a monthly time step showed that only July and August had surpluses,with average infiltrations of 25.4 mm and 23.9 mm for 2018 and an RFU of 50 mm.For 2021,the average infiltrations were 30.8 mm and 6.6 mm,respectively,for August and September,and for the same RFU.The water conductivity values between 115 and 800μS·cm^(-1).The hydrogen potential varied between 5 and 7 pH units,giving the water an acidic character that makes it corrosive to equipment.展开更多
High-pressure die cast(HPDC)AZ91 magnesium alloy is widely used in automotive components such as transmission housings and brackets for its excellent strength-to-weight ratio.Zinc-based cold spray coatings can be appl...High-pressure die cast(HPDC)AZ91 magnesium alloy is widely used in automotive components such as transmission housings and brackets for its excellent strength-to-weight ratio.Zinc-based cold spray coatings can be applied selectively to vulnerable areas to enhance corrosion resistance,minimize galvanic coupling with dissimilar metals,and eliminate the need for full-surface oxide coatings,making the process more efficient and targeted.A comprehensive evaluation of 16 combinations of nitrogen carrier gas temperatures and pressures led to the identification of an optimal range of process parameters,yielding Zn coatings with porosity<0.5% by area,wear rates reduced by a factor of two compared to uncoated AZ91,and adhesion strengths up to 35 MPa.The enhanced mechanical performance of the coating is attributed to the low porosity and the formation of a metallurgical bond at the coating-substrate interface.Corrosion studies using macroscale potentiodynamic polarization(PDP)and electrochemical impedance spectroscopy(EIS)revealed a significant decrease in corrosion rate and a shift to more noble corrosion potentials(ZCP)for coated substrates.Furthermore,the Zn cold-sprayed samples exhibited significantly lower corrosioninduced evolved hydrogen content compared to the base AZ91 substrate and AZ91 coated with industrial coatings,demonstrating that the Zn layer effectively protects the substrate from the corrosive environment.Overall,cold spray Zn coatings significantly improve the mechanical and corrosion performance of AZ91 Mg alloys,addressing key material challenges and enabling their broader use in automotive applications.展开更多
A discontinuous smoothed particle hydrodynamics(DSPH)method considering block contacts is originally developed to model the cracking,frictional slip and large deformation in rock masses,and is verified by theoretical,...A discontinuous smoothed particle hydrodynamics(DSPH)method considering block contacts is originally developed to model the cracking,frictional slip and large deformation in rock masses,and is verified by theoretical,numerical and/or experimental results.In the DSPH method,cracking is realized by breaking the virtual bonds via a pseudo-spring method based on Mohr–Coulomb failure criteria.The damaged particles are instantaneously replaced by discontinuous particles and the contact bond between the original and discontinuous particles is formed to simulate the frictional slip and separation/contraction between fracture surfaces based on the block contact algorithm.The motion of rock blocks and the contact force of discontinuous particles are determined following Newton's second law.The results indicate that the DSPH method precisely captures the cracking,contact formation and complete failure across six numerical benchmark tests.This single smoothed particle hydrodynamics(SPH)framework could significantly improve computational efficiency and is potentially applicable to broad multi-physical rock engineering problems of different scales.展开更多
This paper experimentally investigates the wave pressure and pore pressure within a sandy seabed around two pipelines under the action of random waves(currents).The experiments revealed that when the random wave plus ...This paper experimentally investigates the wave pressure and pore pressure within a sandy seabed around two pipelines under the action of random waves(currents).The experiments revealed that when the random wave plus current cases are compared with the random wave-only case,the forward current promotes wave propagation,whereas the reversed backward current inhibits wave propagation.Furthermore,the wave pressure on the downstream pipeline decreases as the relative spacing ratio increases and increases as the diameter increases.However,alterations in the relative spacing ratio or dimensions of the downstream pipeline exert a negligible influence on the wave pressure of the upstream pipeline.Moreover,the relative spacing ratio between the pipelines and the dimensions of the pipelines considerably influence the pore pressure in the sand bed.When the relative spacing ratio remains constant,increasing the downstream pipeline diameter will increase the pore-water pressure of the soil below the downstream pipeline.展开更多
Submarine landslides frequently occur on continental margins and slopes,thereby causing serious damage to offshore structures.Therefore,analyzing their motion behavior and predicting their impact forces are crucial.In...Submarine landslides frequently occur on continental margins and slopes,thereby causing serious damage to offshore structures.Therefore,analyzing their motion behavior and predicting their impact forces are crucial.In this work,the smooth particle hydrodynamics(SPH)algorithm is used in the development of a multiphase flow model for submarine landslides.The underwater landslide and the ambient water are simulated using the non-Newtonian and Newtonian fluid models,respectively.An artificial diffusion term of density is incorporated in the governing equation,and the equation of state is modified to improve the stability and accuracy of the SPH model.Three benchmark problems are simulated using the SPH model.The effect of SPH particle size on the simulated results is also explored.The effects of the rheological parameters on the landslide motion behavior are investigated by conducting a sensitivity analysis.Numerical results fit the experimental data well,indicating the good stability of the SPH model and its accuracy in simulating the motion and impact behavior of submarine landslides.展开更多
The understanding of the impact of high-velocity microparticles on human skin tissue is important for the ad-ministration of drugs during transdermal drug delivery.This paper aims to numerically investigate the dynami...The understanding of the impact of high-velocity microparticles on human skin tissue is important for the ad-ministration of drugs during transdermal drug delivery.This paper aims to numerically investigate the dynamic behavior of human skin tissue under micro-particle impact in transdermal drug delivery.The numerical model was developed based on a coupled smoothed particle hydrodynamics(SPH)and FEM method via commercial FE software RADIOSS.Analytical analysis was conducted applying the Poncelet model and was used as validation data.A hyperelastic one-term Ogden model with one pair of material parameters(μ,α)was implemented for the skin tissue.Sensitivity studies reveal that the effect of parameter α on the penetration process is much more significant than μ.Numerical results correlate well with the analytical curves with various particle diameters and impact velocities,its capability of predicting the penetration process of micro-particle impacts into skin tissues.This work can be further investigated to guide the design of transdermal drug delivery equipment.展开更多
Flows and transport phenomena in confined spaces have emerged as a key direction in modern fluid dynamics research[1].Scaling down the hydrodynamic length of a system does not simply lead to a laminar flow in low Reyn...Flows and transport phenomena in confined spaces have emerged as a key direction in modern fluid dynamics research[1].Scaling down the hydrodynamic length of a system does not simply lead to a laminar flow in low Reynolds number,but reveals plenty of new phenomena with novel technological implications.Unlike in macroscale systems,fluid behavior at micro-and nanoscales is governed by forces that act at or near the interfaces,including surface tension,wettability,van der Waals interactions,and electrostatic effects,etc.These interfacial forces produce new hydrodynamics and mass transport phenomena that have not been observed on large scales,which are widely used in multidisciplinary areas.展开更多
Spin polarization and spin transport are common phenomena in many quantum systems.Relativistic spin hydrodynamics provides an effective low-energy framework to describe these processes in quantum many-body systems.The...Spin polarization and spin transport are common phenomena in many quantum systems.Relativistic spin hydrodynamics provides an effective low-energy framework to describe these processes in quantum many-body systems.The fundamental symmetry underlying relativistic spin hydrodynamics is angular momentum conservation,which naturally leads to interconversion between spin and orbital angular momenta.This inter-conversion is a key feature of relativistic spin hydrodynamics,which is closely related to entropy production and introduces ambiguity in the construction of constitutive relations.In this article,we present a pedagogical introduction of relativistic spin hydrodynamics.We demonstrate how to derive constitutive relations by applying local thermodynamic laws and explore several distinctive aspects of spin hydrodynamics.These include pseudo-gauge ambiguity,the behavior of the system in the presence of strong vorticity,and the challenges of modeling the freeze-out of spin in heavy-ion collisions.We also outline some future prospects for spin hydrodynamics.展开更多
This study presents a detailed experimental evaluation of a newly developed mechanistic scale-up methodology for gas-solid fluidized beds.Traditional scale-up approaches typically rely on matching global dimensionless...This study presents a detailed experimental evaluation of a newly developed mechanistic scale-up methodology for gas-solid fluidized beds.Traditional scale-up approaches typically rely on matching global dimensionless groups,which often fail to ensure local hydrodynamic similarity.In contrast,the new mechanistic method aims to achieve scale-up by matching the radial profiles of gas holdup between geometrically similar beds at corresponding dimensionless axial positions(z/Dc).This approach is based on the premise that when gas holdup profiles align,other key hydrodynamic parameters—such as solids holdup and particle velocity—also become similar.To validate this methodology,experiments were conducted in two fluidized beds with inner diameters of 14 cm and 44 cm.Optical probes and gamma ray densitometry(GRD)were used to measure local gas holdup,solids holdup,and particle velocity at multiple axial and radial positions.The results show that matched gas holdup profiles led to mean absolute deviations(MAD)below 3%in solids holdup and particle velocity,confirming hydrodynamic similarity.In contrast,unmatched profiles resulted in significant deviations across all parameters.展开更多
基金The National Natural Science Foundation of China(Grant No.52201376)the Natural Science Foundation of Hubei Province,China(Grant No.2023AFB683).
文摘In this investigation,a hybrid approach integrating the IDDES turbulence model and FW-H is employed to forecast the hydroacoustic of the rim driven thruster(RDT)under non-cavitation and uniform flow conditions at varying loading conditions(J=0.3 and J=0.6).It is revealed that the quadrupole term contribution in the P-FWH method significantly affects the monopole term in the low-frequency region,while it mainly affects the dipole term in the high-frequency region.Specifically,the overall sound pressure levels(SPL)of the RDT using the P-FWH method are 2.27 dB,10.03 dB,and 16.73 dB at the receiving points from R1 to R3 under the heavy-loaded condition,while they increase by 0.67 dB at R1,and decrease by 14.93 dB at R2,and 22.20 dB at R3,for the light-loaded condition.The study also utilizes the pressure-time derivatives to visualize the numerical noise and to pinpoint the dynamics of the vortex cores,and the optimization of the grid design can significantly reduce the numerical noise.The computational accuracy of the P-FWH method can meet the noise requirements for the preliminary design of rim driven thrusters.
基金supported by European Union funding(PON“Ricerca e Innovazione”2014‒2020).
文摘The issue of resistance reduction through hull ventilation is of particular interest in contemporary research.This paper presents multiphase computational fluid dynamics(CFD)simulations with 2-DOF motion of a planing hull.The original hull was modified by introducing a step to allow air ventilation.Following an assessment of the hull performance,a simulation campaign in calm water was conducted to characterize the hull at various forward speeds and air insufflation rates for a defined single step geometry.Geometric analysis of the air layer thickness beneath the hull for each simulated condition was performed using a novel method for visualizing local air thickness.Additionally,two new parameters were introduced to understand the influence of spray rails on the air volume beneath the hull and to indicate the primary direction of ventilated air escape.A validation campaign and an assessment of uncertainty of the simulation has been conducted.The features offered by the CFD methodology include the evaluation of the air layer thickness as a function of hull velocity and injection flow rate and the air volume distribution beneath the hull.The air injection velocity can be adjusted across various operating conditions,thereby preventing performance or efficiency loss during navigation.Based on these findings,the study highlights the benefits of air insufflation in reducing hull resistance for high-speed planing vessels.This work lays a robust foundation for future research and new promising topics,as the exploration of air insufflation continues to be a topic of contemporary interest within naval architecture and hydrodynamics.
文摘The present study focuses on the flow of a yield-stress(Bingham)nanofluid,consisting of suspended Fe3O4 nanoparticles,subjected to a magnetic field in a backward-facing step duct(BFS)configuration.The duct is equipped with a cylindrical obstacle,where the lower wall is kept at a constant temperature.The yield-stress nanofluid enters this duct at a cold temperature with fully developed velocity.The aim of the present investigation is to explore the influence of flow velocity(Re=10 to 200),nanoparticle concentration(ϕ=0 to 0.1),magnetic field intensity(Ha=0 to 100),and its inclination angle(γ=0 to 90)and nanofluid yield stress(Bn=0 to 20)on the thermal and hydrodynamic efficiency inside the backward-facing step.The numerical results have been obtained by resolving the momentum and energy balance equations using the Galerkin finite element method.The obtained results have indicated that an increase in Reynolds number and nanoparticle volume fraction enhances heat transfer.In contrast,a significant reduction is observed with an increase in Hartmann and Bingham numbers,resulting in quasi-immobilization of the fluid under the magnetic influence and radical solidification of this type of fluid,accompanied by the suppression of the vortex zone downstream of the cylindrical obstacle.This study sheds light on the complexity of this magnetically influenced fluid,with potential implications in various engineering and materials science fields.
基金The insights gained through these works,particularly from projects IITD/IRD/CW14168,CW14469,and CW14378,have significantly contributed to the development of the analysis presented in this study。
文摘Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures worldwide.An understanding of the liquefaction triggering,and the post-failure large deformation behaviour is essential for designing resilient infrastructure.The present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of geotechnical structures.The coupled flowdeformation behaviour of soils subjected to cyclic loading is described using the PM4Sand model implemented in a three-phase,single-layer SPH framework.A staggered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energy modes and tensile instability.Further,non-reflecting boundary conditions for seismic analysis of semi-infinite soil domains using the SPH method are proposed.The numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level ground site,and liquefaction-induced failure of the Lower San Fernando Dam.Satisfactory agreement for liquefaction triggering and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading on field-scale geotechnical structures.The present study also serves as the basis for future advancements of the SPH method for applications related to earthquake geotechnical engineering.
基金National Natural Science Foundation of China(12471367)。
文摘In this work,we present a parallel implementation of radiation hydrodynamics coupled with particle transport,utilizing software infrastructure JASMIN(J Adaptive Structured Meshes applications INfrastructure)which encapsulates high-performance technology for the numerical simulation of complex applications.Two serial codes,radiation hydrodynamics RH2D and particle transport Sn2D,have been integrated into RHSn2D on JASMIN infrastructure,which can efficiently use thousands of processors to simulate the complex multi-physics phenomena.Moreover,the non-conforming processors strategy has ensured RHSn2D against the serious load imbalance between radiation hydrodynamics and particle transport for large scale parallel simulations.Numerical results show that RHSn2D achieves a parallel efficiency of 17.1%using 90720 cells on 8192 processors compared with 256 processors in the same problem.
基金supported by the Swedish Research Council(VR)under grant number 2020-05044by the research environment grant"Gravitational Radiation and Electromagnetic Astrophysical Transients"(GREAT)funded by the Swedish Research Council(VR)under Dnr 2016-06012+2 种基金by the Knut and Alice Wallenberg Foundation under grant Dnr.KAW 2019.0112by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany's Excellence Strategy-EXC 2121"Quantum Universe"-390833306by the European Research Council(ERC)Advanced Grant INSPIRATION under the European Union's Horizon 2020 Research and Innovation Programme(Grant agreement No.101053985).
文摘We present and explore a new shock-capturing particle hydrodynamics approach.Our starting point is a commonly used discretization of smoothed particle hydrodynamics.We enhance this discretization with Roe’s approx-imate Riemann solver,we identify its dissipative terms,and in these terms,we use slope-limited linear reconstruction.All gradients needed for our method are calculated with linearly reproducing kernels that are constructed to enforce the two lowest-order consistency relations.We scrutinize our reproducing kernel implementation carefully on a“glass-like”particle distribution,and we find that constant and linear functions are recovered to machine precision.We probe our method in a series of challenging 3D benchmark problems ranging from shocks over instabilities to Schulz-Rinne-type vorticity-creating shocks.All of our simulations show excellent agreement with analytic/reference solutions.
基金National Key Research and Development Program of China,Grant/Award Number:2022YFC3204202National Natural Science Foundation of China,Grant/Award Number:52122904Ministry of Water Resources,Grant/Award Number:SKS-2022121。
文摘Fish swimming hydrodynamics serves as a critical foundation for aquatic ecological conservation,with recent research extending from 2D to 3D perspectives.This study employs 3D high-fidelity modeling with dynamic mesh technology to investigate how cylindrical obstacles at varying positions affect Carassius auratus locomotion.Analysis of nine configurations reveals bidirectional flow interactions between fish and cylinders,with cylinder wake influence persisting at 1-2 times the total length intervals but diminishing at 3times.Compared with swimming in uniform flow,the mechanical benefit of C.auratus located 2 times the total length directly behind the cylinder is the largest,and its value reaches 4.19 times.Wavelet analysis of 30-cycle mechanical data demonstrates closer intervals enhance benefit magnitude,whereas greater distances accelerate benefit realization.These 3D computational findings corroborate 2D studies while providing new spatial interaction insights,offering theoretical foundations for fish conservation strategies related to hydraulic structures.
基金supported by the National Natural Science Foundation of China(Grant No.12172330)the National Key R&D Program of China(Grant No.2022YFA1203200).
文摘A comprehensive understanding of surface wetting phenomena in microchannels is essential for optimizing particle transport and filtration processes.This study numerically investigates the dynamics of a freely suspended elliptical cylinder in confined Poiseuille flow,with a focus on Navier slip boundary conditions.The smoothed particle hydrodynamics method is employed,which is advantageous for its Lagrangian framework in handling dynamic fluid-solid interfaces with slip.Our results demonstrate that the slip conditions enable precise control over inertial focusing positions and particle motion modes.Compared to no-slip scenarios,unilateral wall slip induces two novel motion types:“leaning”and“rolling”.When equal slip lengths are applied to both walls,even small slip values facilitate off-center inertial focusing and elevate equilibrium positions.Slip on the cylinder surface further enhances inertial lift while suppressing rotational dynamics.In particular,under strong confinement or with large particle-surface slip lengths,we identify an additional distinct motion regime termed“inclined.”These findings provide new insights for active particle manipulation in microfluidic applications.
基金supported by the Sanya Science and Education Innovation Park of Wuhan University of Technology(Grant No.2022KF0017)Hainan Provincial Natural Science Foundation of China(Grant No.522QN342)+1 种基金the National Natural Science Foundation of China(Grant No.52201376)Natural Science Foundation of Hubei Province,China(Grant No.2023AFB683).
文摘This study aims to enhance the maneuvering advantages of the waterjet unit through parametric design,performance evaluation,and optimization of the one-piece waterjet propulsion steering and reversing gear(SRG).The SRG’s performance evaluation stems mainly from the effect of the free surface,the varying sailing speeds of the ship,and its performance while functioning at the stern of the waterjet-propelled vessel.Parameters such as the length,width,and height of the steering gear,as well as the inclination,width,and curvature of the reversing gear,significantly influence the SRG.Although the free surface has a great impact on the force of the SRG,its performance trend remains unaffected.When the SRG operates at the stern of the ship,the optimized scheme’s lateral force improves by an average of 8.08%for sailing with a rudder angle condition and an average of 45.69%for reversing sailing with a rudder angle condition.The longitudinal force of the optimized scheme improves by more than 23%when sailing without a rudder angle condition and by an average of 31.75%when sailing with a reversed rudder angle condition.Additionally,the speed of the rotor has a minimal effect on the lateral force and a significant effect on the longitudinal force.
基金financially supported by the Basic and Applied Basic Research Foundation of Guangdong Province(Grant Nos.2023A1515010890 and 2022A1515240039)the National Natural Science Foundation of China(Grant No.52001071)+4 种基金the Special Fund Competition Allocation Project of Guangdong Science and Technology Innovation Strategy(Grant No.2023A01022)the Non-funded Science and Technology Research Program Project of Zhanjiang(Grant No.2021B01416)Student Innovation Team Project of Guangdong Ocean University(Grant No.CXTD2023012)the Doctor Initiate Projects of Guangdong Ocean University(Grant Nos.060302072103 and R20068)the Marine Youth Talent Innovation Project of Zhanjiang(Grant No.2021E05009).
文摘The interaction between extreme waves and structures is a crucial study area in marine science,as it significantly influences safety and disaster prevention strategies for marine and coastal engineering.To investigate the flow field of a semi-submersible against extreme waves,a model simulating solitary wave interactions with the semi-submersible system was developed via the meshless smoothed particle hydrodynamics(SPH)method and Rayleigh’s theory.Notably,the wave surface and wave load results obtained from the SPH model,compared with those of OpenFOAM,result in an interaction test case between solitary waves and partially submerged rectangular obstacles and show good agreement,with a maximum relative error of 3.4%.An analysis of the calculated results of the semi-submersible facing solitary waves revealed several key findings:overtopping,which decreases with increasing water depth,occurs on the structure when the non-submerged ratio is 0.33 and the wave height surpasses 0.2 m.The transmission coefficient decreases with increasing wave height but increases as the water depth increases.Furthermore,the reflection coefficient peaks at a wave height H0=0.2 m.The dissipation coefficient displays a valley trend with a small water depth,whereas it increases monotonically with increasing water depth.The dissipation coefficient decreases with increasing water depth.
基金financially supported by the Riset Pengembangan dan Penerapan(RPP),Diponegoro University 2023 research scheme with contract number 609-18/UN7.D2/PP/VIII/2023.
文摘Shallow water infrastructure needs to support increased activity on the shores of Semarang.This study chooses several pontoons because of their good stability,rolling motion,and more expansive space.A coupled simulation method consisting of hydrodynamic and structural calculations has been used to evaluate a catamaran pontoon’s motion and structural integrity.Four different space sizes are set for the pontoon system:5 m,5.5 m,6 m,and 6.5 m.The frequency domain shows that the pontoon space affects the RAO in wave periods ranging from 3 s to 5 s.At wave periods of 3 s,4 s,and 5 s,the pontoon space significantly affects the maximum motion and chain tension parameter values,which are evaluated via time domain simulation.The critical stress of the pontoon is shown at a wave period of 5 s for 5 m and 5.5 m of pontoon space,which shows that the stress can reach 248 MPa.
文摘In the Maradi region,the alluvial aquifer of the Goulbi’N Maradi rests on the aquifers of the Continental Hamadien.It represents an essential reserve for irrigation and drinking water supply.However,due to its high demand and the excessive use of chemical fertilizers and pesticides in irrigation,a ten-year analysis of the dynamics of this alluvial aquifer has proven necessary.Hence,this study,based on hydrodynamic and hydrochemical approaches,aims to improve knowledge of the dynamics of the alluvial aquifer from 2015 to 2023.The novelty of this study lies in its comprehensive coverage of the entire Goulbi N’Maradi valley in Niger,employing a multidimensional approach.The data used were composed of water samples taken from forty-five structures,piezometric monitoring sheets,and digital terrain models.The results reveal that the Goulbi’N Maradi aquifer exhibits continuous piezometry,characterized by a general flow pattern from south to northwest and a relatively strong hydraulic gradient in the southern part,indicating recharge from recent infiltration of rain and floodwaters.The water balances calculated at a monthly time step showed that only July and August had surpluses,with average infiltrations of 25.4 mm and 23.9 mm for 2018 and an RFU of 50 mm.For 2021,the average infiltrations were 30.8 mm and 6.6 mm,respectively,for August and September,and for the same RFU.The water conductivity values between 115 and 800μS·cm^(-1).The hydrogen potential varied between 5 and 7 pH units,giving the water an acidic character that makes it corrosive to equipment.
基金the support of the U.S.Department of Energy’s Vehicle Technologies Office.
文摘High-pressure die cast(HPDC)AZ91 magnesium alloy is widely used in automotive components such as transmission housings and brackets for its excellent strength-to-weight ratio.Zinc-based cold spray coatings can be applied selectively to vulnerable areas to enhance corrosion resistance,minimize galvanic coupling with dissimilar metals,and eliminate the need for full-surface oxide coatings,making the process more efficient and targeted.A comprehensive evaluation of 16 combinations of nitrogen carrier gas temperatures and pressures led to the identification of an optimal range of process parameters,yielding Zn coatings with porosity<0.5% by area,wear rates reduced by a factor of two compared to uncoated AZ91,and adhesion strengths up to 35 MPa.The enhanced mechanical performance of the coating is attributed to the low porosity and the formation of a metallurgical bond at the coating-substrate interface.Corrosion studies using macroscale potentiodynamic polarization(PDP)and electrochemical impedance spectroscopy(EIS)revealed a significant decrease in corrosion rate and a shift to more noble corrosion potentials(ZCP)for coated substrates.Furthermore,the Zn cold-sprayed samples exhibited significantly lower corrosioninduced evolved hydrogen content compared to the base AZ91 substrate and AZ91 coated with industrial coatings,demonstrating that the Zn layer effectively protects the substrate from the corrosive environment.Overall,cold spray Zn coatings significantly improve the mechanical and corrosion performance of AZ91 Mg alloys,addressing key material challenges and enabling their broader use in automotive applications.
基金financial support from the National Key Research and Development Program of China(Grant No.2019YFC1509702)the Fundamental Research Funds for the Central Universities in Chinathe National Natural Science Foundation of China(Grant No.42377162).
文摘A discontinuous smoothed particle hydrodynamics(DSPH)method considering block contacts is originally developed to model the cracking,frictional slip and large deformation in rock masses,and is verified by theoretical,numerical and/or experimental results.In the DSPH method,cracking is realized by breaking the virtual bonds via a pseudo-spring method based on Mohr–Coulomb failure criteria.The damaged particles are instantaneously replaced by discontinuous particles and the contact bond between the original and discontinuous particles is formed to simulate the frictional slip and separation/contraction between fracture surfaces based on the block contact algorithm.The motion of rock blocks and the contact force of discontinuous particles are determined following Newton's second law.The results indicate that the DSPH method precisely captures the cracking,contact formation and complete failure across six numerical benchmark tests.This single smoothed particle hydrodynamics(SPH)framework could significantly improve computational efficiency and is potentially applicable to broad multi-physical rock engineering problems of different scales.
基金supported by the National Natural Science Foundation of China(Grant No.52271281)Shandong Provincial High-Level Talent Workstation,Shandong Province Natural Science Foundation Youth project(Grant No.ZR2023QE190)an Open funding project from the Key Laboratory of Ministry of Education for Coastal Disaster and Protection,Hohai University,China(Grant No.202206).
文摘This paper experimentally investigates the wave pressure and pore pressure within a sandy seabed around two pipelines under the action of random waves(currents).The experiments revealed that when the random wave plus current cases are compared with the random wave-only case,the forward current promotes wave propagation,whereas the reversed backward current inhibits wave propagation.Furthermore,the wave pressure on the downstream pipeline decreases as the relative spacing ratio increases and increases as the diameter increases.However,alterations in the relative spacing ratio or dimensions of the downstream pipeline exert a negligible influence on the wave pressure of the upstream pipeline.Moreover,the relative spacing ratio between the pipelines and the dimensions of the pipelines considerably influence the pore pressure in the sand bed.When the relative spacing ratio remains constant,increasing the downstream pipeline diameter will increase the pore-water pressure of the soil below the downstream pipeline.
基金supported by the National Natural Science Foundation of China(Nos.42472332,42102318 and 42006143)the Open Research Fund Program of Zhoushan Field Scientific Observation and Research Station for Marine Geo-Hazards,China Geological Survey(No.ZSORS22-07)+1 种基金the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning(No.TP2019037)the Open Research Fund Program of Marine Ecological Restoration and Smart Ocean Engineering Research Center of Hebei Province(No.HB MESO2312)。
文摘Submarine landslides frequently occur on continental margins and slopes,thereby causing serious damage to offshore structures.Therefore,analyzing their motion behavior and predicting their impact forces are crucial.In this work,the smooth particle hydrodynamics(SPH)algorithm is used in the development of a multiphase flow model for submarine landslides.The underwater landslide and the ambient water are simulated using the non-Newtonian and Newtonian fluid models,respectively.An artificial diffusion term of density is incorporated in the governing equation,and the equation of state is modified to improve the stability and accuracy of the SPH model.Three benchmark problems are simulated using the SPH model.The effect of SPH particle size on the simulated results is also explored.The effects of the rheological parameters on the landslide motion behavior are investigated by conducting a sensitivity analysis.Numerical results fit the experimental data well,indicating the good stability of the SPH model and its accuracy in simulating the motion and impact behavior of submarine landslides.
基金supported by the Nanjing Institute of Technology(Grant No.YKJ202301).
文摘The understanding of the impact of high-velocity microparticles on human skin tissue is important for the ad-ministration of drugs during transdermal drug delivery.This paper aims to numerically investigate the dynamic behavior of human skin tissue under micro-particle impact in transdermal drug delivery.The numerical model was developed based on a coupled smoothed particle hydrodynamics(SPH)and FEM method via commercial FE software RADIOSS.Analytical analysis was conducted applying the Poncelet model and was used as validation data.A hyperelastic one-term Ogden model with one pair of material parameters(μ,α)was implemented for the skin tissue.Sensitivity studies reveal that the effect of parameter α on the penetration process is much more significant than μ.Numerical results correlate well with the analytical curves with various particle diameters and impact velocities,its capability of predicting the penetration process of micro-particle impacts into skin tissues.This work can be further investigated to guide the design of transdermal drug delivery equipment.
文摘Flows and transport phenomena in confined spaces have emerged as a key direction in modern fluid dynamics research[1].Scaling down the hydrodynamic length of a system does not simply lead to a laminar flow in low Reynolds number,but reveals plenty of new phenomena with novel technological implications.Unlike in macroscale systems,fluid behavior at micro-and nanoscales is governed by forces that act at or near the interfaces,including surface tension,wettability,van der Waals interactions,and electrostatic effects,etc.These interfacial forces produce new hydrodynamics and mass transport phenomena that have not been observed on large scales,which are widely used in multidisciplinary areas.
基金supported by the Natural Science Foundation of Shanghai(No.23JC1400200)National Natural Science Foundation of China(Nos.12225502,12075061,and 12147101)the National Key Research and Development Program of China(No.2022YFA1604900)。
文摘Spin polarization and spin transport are common phenomena in many quantum systems.Relativistic spin hydrodynamics provides an effective low-energy framework to describe these processes in quantum many-body systems.The fundamental symmetry underlying relativistic spin hydrodynamics is angular momentum conservation,which naturally leads to interconversion between spin and orbital angular momenta.This inter-conversion is a key feature of relativistic spin hydrodynamics,which is closely related to entropy production and introduces ambiguity in the construction of constitutive relations.In this article,we present a pedagogical introduction of relativistic spin hydrodynamics.We demonstrate how to derive constitutive relations by applying local thermodynamic laws and explore several distinctive aspects of spin hydrodynamics.These include pseudo-gauge ambiguity,the behavior of the system in the presence of strong vorticity,and the challenges of modeling the freeze-out of spin in heavy-ion collisions.We also outline some future prospects for spin hydrodynamics.
文摘This study presents a detailed experimental evaluation of a newly developed mechanistic scale-up methodology for gas-solid fluidized beds.Traditional scale-up approaches typically rely on matching global dimensionless groups,which often fail to ensure local hydrodynamic similarity.In contrast,the new mechanistic method aims to achieve scale-up by matching the radial profiles of gas holdup between geometrically similar beds at corresponding dimensionless axial positions(z/Dc).This approach is based on the premise that when gas holdup profiles align,other key hydrodynamic parameters—such as solids holdup and particle velocity—also become similar.To validate this methodology,experiments were conducted in two fluidized beds with inner diameters of 14 cm and 44 cm.Optical probes and gamma ray densitometry(GRD)were used to measure local gas holdup,solids holdup,and particle velocity at multiple axial and radial positions.The results show that matched gas holdup profiles led to mean absolute deviations(MAD)below 3%in solids holdup and particle velocity,confirming hydrodynamic similarity.In contrast,unmatched profiles resulted in significant deviations across all parameters.
