Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression an...Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression and permeability tests to investigate the mechanical and seepage properties of tight sandstone.A digital core of tight sandstone was built using Computed Tomography(CT)scanning,which was divided into matrix and pore phases by a pore equivalent diameter threshold.A fluid-solid coupling model was established to investigate the seepage characteristics at micro-scale.The results showed that increasing the confining pressure decreased porosity,permeability,and flow velocity,with the pore phase becoming the dominant seepage channel.Cracks and large pores closed first under increasing pressure,resulted in a steep drop in permeability.However,permeability slightly decreased under high confining pressure,which followed a first-order exponential function.Flow velocity increased with seepage pressure.And the damage mainly occurred in stress-concentration regions under low seepage pressure.Seepage behavior followed linear Darcy flow,the damage emerged at seepage entrances under high pressure,which decreased rock elastic modulus and significantly increased permeability.展开更多
Deep underground excavation causes considerable unloading effects,leading to a pronounced bias pressure phenomenon.The deformation and seepage characteristics of rock masses under different gas and confining pressures...Deep underground excavation causes considerable unloading effects,leading to a pronounced bias pressure phenomenon.The deformation and seepage characteristics of rock masses under different gas and confining pressures were investigated via triaxial loading and unloading seepage tests.When the influential coefficient of effective confining pressure(β)is less than 0.065,the seepage force considerably weakens the strength of fractured rock masses.Conversely,whenβis greater than 0.065,the opposite is true.Moreover,the increase in the axial load leads to an increase in the precast fracture volumetric strain,which is the main reason for the increase in fracture permeability.This effect is particularly significant during the unloading stage.Based on the test results,a method for calculating the dynamic seepage evolution of rock masses,considering the effects of rock mass damage and fracture deformation,is introduced,and the effectiveness of the calculation is validated.The entire description of the seepage under loading and unloading was accomplished.The equivalent relationship between the lateral and normal stresses on fracture surfaces ranges from 0.001 to 0.1,showing an exponential variation between the lateral stress influence coefficient on normal deformation(χ)and seepage pressure.Before the failure of the rock mass,the seepage in the fractures was in a linear laminar flow state.However,after the failure,when the gas pressure reached 2 MPa,the flow state in the fractures transitioned to nonlinear laminar flow.The results are important for predicting hazardous gas leaks during deep underground engineering excavation.展开更多
Hydraulic fracturing technology has played an important role in the exploitation of unconventional oil and gas resources,however,its application to gas hydrate reservoirs has been rarely studied.Currently,there is sti...Hydraulic fracturing technology has played an important role in the exploitation of unconventional oil and gas resources,however,its application to gas hydrate reservoirs has been rarely studied.Currently,there is still limited understanding of the propagation and extension of fractures around the wellbore during the fracturing process of horizontal wells in hydrate reservoirs,as well as the stress interference patterns between fractures.This study simulates hydraulic fracturing processes in hydrate reservoirs using a fluidsolid coupling discrete element method(DEM),and analyzes the impacts of hydrate saturation and geological and engineering factors on fracture extension and stress disturbance.The results show that hydraulic fracturing is more effective when hydrate saturation exceeds 30%and that fracture pressure increases with saturation.The increase in horizontal stress differential enhances the directionality of fracture propagation and reduces stress disturbance.The distribution uniformity index(DUI)reveals that injection pressure is directly proportional to the number of main fractures and inversely proportional to fracturing time,with fracturing efficiency depending on the spacing between injection points and the distance between wells.This work may provide reference for the commercial exploitation of natural gas hydrates.展开更多
The coupled nonlocal nonlinear Schrödinger equations with variable coefficients are researched using the nonstandard Hirota bilinear method.The two-soliton and double-hump one-soliton solutions for the equations ...The coupled nonlocal nonlinear Schrödinger equations with variable coefficients are researched using the nonstandard Hirota bilinear method.The two-soliton and double-hump one-soliton solutions for the equations are first obtained.By assigning different functions to the variable coefficients,we obtain V-shaped,Y-shaped,wave-type,exponential solitons,and so on.Next,we reveal the influence of the real and imaginary parts of the wave numbers on the double-hump structure based on the soliton solutions.Finally,by setting different wave numbers,we can change the distance and transmission direction of the solitons to analyze their dynamic behavior during collisions.This study establishes a theoretical framework for controlling the dynamics of optical fiber in nonlocal nonlinear systems.展开更多
In the context of global warming and intensified human activities,glacier instability in plateau regions has increased,and glacier debris flows have become active,which poses a significant threat to the lives and prop...In the context of global warming and intensified human activities,glacier instability in plateau regions has increased,and glacier debris flows have become active,which poses a significant threat to the lives and property of people and socioeconomic development.The mass movement process of glacier debris flows is extremely complex,so this paper uses the 2018 Sedongpu glacier debris flow event on the Qinghai-Tibet Plateau as an example and applies a numerical simulation method to invert the whole process of mass movement.In view of the interaction between phases in the process of motion,we use the fluid-solid coupling method to describe the mass movement.The granular-flow model and drift-flux model are employed in FLOW3D software to study the mass movement process of glacier debris flows and explore their dynamic characteristics.The results indicate that the glacier debris flow lasted for 700 s,and the movement process was roughly divided into four stages,including initiation,scraping,surging and deposition;the depositional characteristics calculated by the fluid-solid coupling model are consistent with the actual survey results and have good reliability;strong erosion occurs during the mass movement,the clear volume amplification effect,and the first wave climbs 17.8 m across the slope.The fluid-solid coupling method can better simulate glacier debris flows in plateau regions,which is helpful for the study of the mechanism and dynamic characteristics of such disasters.展开更多
This paper introduces MultiPHydro,an in-house computational solver developed for simulating hydrodynamic and multiphase fluid—body interaction problems,with a specialized focus on multiphase flow dynamics.The solver ...This paper introduces MultiPHydro,an in-house computational solver developed for simulating hydrodynamic and multiphase fluid—body interaction problems,with a specialized focus on multiphase flow dynamics.The solver employs the boundary data immersion method(BDIM)as its core numerical framework for handling fluid—solid interfaces.We briefly outline the governing equations and physical models integrated within MultiPHydro,including weakly-compressible flows,cavitation modeling,and the volume of fluid(VOF)method with piecewise-linear interface reconstruction.The solver’s accuracy and versatility are demonstrated through several numerical benchmarks:single-phase flow past a cylinder shows less than 10%error in vortex shedding frequency and under 4%error in hydrodynamic resistance;cavitating flows around a hydrofoil yield errors below 7%in maximum cavity length;water-entry cases exhibit under 5%error in displacement and velocity;and water-exit simulations predict cavity length within 7.2%deviation.These results confirm the solver’s capability to reliably model complex fluid-body interactions across various regimes.Future developments will focus on refining mathematical models,improving the modeling of phase-interaction mechanisms,and implementing GPU-accelerated parallel algorithms to enhance compatibility with domestically-developed operating systems and deep computing units(DCUs).展开更多
In this paper,the vegetable field in the teaching base of College of Agriculture,Yangtze University was taken as the research object.The indoor simulation method was used to explore the effects of temperature and mois...In this paper,the vegetable field in the teaching base of College of Agriculture,Yangtze University was taken as the research object.The indoor simulation method was used to explore the effects of temperature and moisture on the phosphorus(P)bioavailability of vegetable soil.Three temperature gradients[T1(15℃),T2(25℃),T3(35℃)]and three humidity gradients[W1(40%),W2(70%),W3(100%)]were set in the test.The results showed that it could improve the contents of HCl-P,Enzyme-P,Citrate-P,and Olsen-P in vegetable soil by increasing soil moisture content;temperature rise was helpful to increase the contents of HCl-P and Olsen-P,but it could reduce the content of Citrate-P.The contents of Enzyme-P and CaCl 2-P were significantly affected by hydrothermal interaction.Within a certain range of soil temperature and humidity,temperature and moisture had a positive coupling effect on soil P bioavailability components,and significantly affected soil P supply capacity.展开更多
We propose a suite of strategies for the parallel solution of fully implicit monolithic fluid-structure interaction(FSI).The solver is based on a modeling approach that uses the velocity and pressure as the primitive ...We propose a suite of strategies for the parallel solution of fully implicit monolithic fluid-structure interaction(FSI).The solver is based on a modeling approach that uses the velocity and pressure as the primitive variables,which offers a bridge between computational fluid dynamics(CFD)and computational structural dynamics.The spatiotemporal discretization leverages the variational multiscale formulation and the generalized-αmethod as a means of providing a robust discrete scheme.In particular,the time integration scheme does not suffer from the overshoot phenomenon and optimally dissipates high-frequency spurious modes in both subproblems of FSI.Based on the chosen fully implicit scheme,we systematically develop a combined suite of nonlinear and linear solver strategies.Invoking a block factorization of the Jacobian matrix,the Newton-Raphson procedure is reduced to solving two smaller linear systems in the multi-corrector stage.The first is of the elliptic type,indicating that the algebraic multigrid method serves as a well-suited option.The second exhibits a two-by-two block structure that is analogous to the system arising in CFD.Inspired by prior studies,the additive Schwarz domain decomposition method and the block-factorization-based preconditioners are invoked to address the linear problem.Since the number of unknowns matches in both subdomains,it is straightforward to balance loads when parallelizing the algorithm for distributed-memory architectures.We use two representative FSI benchmarks to demonstrate the robustness,efficiency,and scalability of the overall FSI solver framework.In particular,it is found that the developed FSI solver is comparable to the CFD solver in several aspects,including fixed-size and isogranular scalability as well as robustness.展开更多
Manipulating magnetic couplings in molecular magnets is of great importance in improving the mag-netic properties of such materials.It has been proved that by adjusting the strength of magnetic cou-plings and the arra...Manipulating magnetic couplings in molecular magnets is of great importance in improving the mag-netic properties of such materials.It has been proved that by adjusting the strength of magnetic cou-plings and the arrangement of the intermolecular magnetic dipoles,magnetic blocking can be significantly enhanced.Herein manipulating the intramolecular dipole interactions by ligand modifica-tion was attempted with the use of three closely related dinuclear Er(Ⅲ)complexes of a common chemical formula of[(COT^(R))Er(μ-CI)(THF)]_(2)(COT^(R)is monosubstituted cyclooctatetraenide dianions with R=diphenylmethylsilyl(Ph_(2)MeS)for 1,triethylsilyl(TES)for 2,and triisopropylsilyl(TIPS)for 3).Each of these complexes features a centrosymmetric dinuclear core unit with their component Er(Ⅲ)ions doubly bridged by two chloro ligands and further coordinated with a capping substituted corR ligand and a coordinated THF molecule.Magnetic studies reveal that the complexes display similar ferromagnetic couplings with comparable single-molecule magnetic behaviors.The ferromagnetic couplings dominated by the intramolecular dipole interactions are found to be 0.7614,0.7380,and 0.5635 cm^(-1)for 1,2,and 3,respectively.The angles(θ)between the magnetic easy axes and the intramolecular Er-Er lines are 24.88(2)°,25.23(1),and 31.85(5),leading to transversal dipole fields of 0.0114,0.0113,and 0.0125 T for 1,2,and 3,respectively.Although the different ligand substitution generates a sizable difference of about 7 in theθangle,the resulting difference in the dipole interactions is not sufficiently strong to cause any significant differences in their magnetic properties.Further change in theθangles to the"side-by-side"(θ=90°)or"head-to-tail"(θ=0°)arrangement of the magnetic easy axes,achievable by rational mo-lecular design,is expected to lead to molecular magnetic materials with much enhanced properties.展开更多
The crossover between short-range and long-range(LR)universal behaviors remains a central theme in the physics of LR interacting systems.The competition between LR coupling and the Berezinskii-Kosterlitz-Thouless mech...The crossover between short-range and long-range(LR)universal behaviors remains a central theme in the physics of LR interacting systems.The competition between LR coupling and the Berezinskii-Kosterlitz-Thouless mechanism makes the problem more subtle and less understood in the two-dimensional(2D)XY model,a cornerstone for investigating low-dimensional phenomena and their implications in quantum computation.We study the 2D XY model with algebraically decaying interaction~1/r^(2+σ).Utilizing an advanced update strategy,we conduct LR Monte Carlo simulations of the model up to a linear size of L=8192.Our results demonstrate continuous phase transitions into a ferromagnetic phase forσ<2,which exhibit the simultaneous emergence of a long-ranged order and a power-law decaying correlation function due to the Goldstone mode.Furthermore,we fnd logarithmic scaling behaviors in the low-temperature phase atσ=2.The observed scaling behaviors in the low-temperature phase forσ≤2 agree with our theoretical analysis.Our fndings request further theoretical understanding and can be of practical application in cutting-edge experiments like Rydberg atom arrays.展开更多
Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineerin...Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineering challenges.This study establishes a multiscale modelling framework coupling the discrete element method(DEM)with multi-body dynamics(MBD)to investigate track-seabed dynamic interactions across three operational modes:flat terrain,slope climbing,and ditch surmounting.The simulation framework,validated against laboratory experiments,systematically evaluates the influence of grouser geometry(involute,triangular,and pin-type)and traveling speed(0.2–1.0 m/s)on traction performance,slip rate,and ground pressure distribution.Results reveal rate-dependent traction mechanisms governed by soil microstructural responses:higher speeds enhance peak traction but exacerbate slip instability on complex terrain.Critical operational thresholds are established—0.7 m/s for flat terrain,≤0.5 m/s for slopes and ditches—with distinct grouser optimization strategies:involute grousers achieve 35%–40%slip reduction on slopes through progressive soil engagement,while triangular grousers provide optimal impact resistance during ditch crossing with 30%–35%performance improvement.These findings provide quantitative design criteria and operational guidelines for optimizing TMV structural parameters and control strategies,offering a robust theoretical foundation for enhancing the performance,safety,and reliability of deep-sea mining equipment in complex submarine environments.展开更多
0 INTRODUCTION Pressure-stress coupling(PSC)refers to the bidirectional mechanical interaction between pore pressure and in-situ stress within subsurface formations(Hillis,2000).Variations in pore pressure redistribut...0 INTRODUCTION Pressure-stress coupling(PSC)refers to the bidirectional mechanical interaction between pore pressure and in-situ stress within subsurface formations(Hillis,2000).Variations in pore pressure redistribute the stress field,while evolving stress states in turn alter pore pressure.This reciprocity,governed by poroelasticity and multiphysics interactions,underlies a wide spectrum of geomechanical processes,including fracture initiation,fluid migration,reservoir evolution,and fault slip or seismicity(Xu et al.,2020).Conventional theories often treat pressure and stress as independent variables.展开更多
Seismic wave propagation in fluid-solid coupled media is currently a popular topic. However, traditional wave equation-based simulation methods have to consider complex boundary conditions at the fluid-solid interface...Seismic wave propagation in fluid-solid coupled media is currently a popular topic. However, traditional wave equation-based simulation methods have to consider complex boundary conditions at the fluid-solid interface. To address this challenge, we propose a novel numerical scheme that integrates the lattice Boltzmann method(LBM) and lattice spring model(LSM). In this scheme, LBM simulates viscoacoustic wave propagation in the fluid area and LSM simulates elastic wave propagation in the solid area. We also introduce three different LBM-LSM coupling strategies, a standard bounce back scheme, a specular reflection scheme, and a hybrid scheme, to describe wave propagation across fluid-solid boundaries. To demonstrate the accuracy of these LBM-LSM coupling schemes, we simulate wave propagation in a two-layer model containing a fluid-solid interface. We place excitation sources in the fluid layer and the solid layer respectively, to observe the wave phenomena when seismic waves propagate to interface from different sides. The simulated results by LBM-LSM are compared with the reference wavefields obtained by the finite difference method(FDM) and the analytical solution(ANA).Our LBM-LSM coupling scheme was verified effective, as the relative errors between the LBM-LSM solutions and reference solutions were within an acceptable range, sometimes around 1.00%. The coupled LBM-LSM scheme is further used to model seismic wavefields across a more realistic rugged seabed,which reveals the potential applications of the coupled LBM-LSM scheme in marine seismic imaging techniques, such as reverse-time migration and full-waveform inversion. The method also has potential applications in simulating wave propagation in complex two-and multi-phase media.展开更多
An integrated coupling element considering wheel-rail interface for analyzing the dynamic responses of vehicle-rail-bridge interaction system with a non-uniform continuous bridge is presented. The governing equations ...An integrated coupling element considering wheel-rail interface for analyzing the dynamic responses of vehicle-rail-bridge interaction system with a non-uniform continuous bridge is presented. The governing equations of the interaction system are established first, and the solution procedure and assembly method of the coupling element are demonstrated. Finally, the accuracy, efficiency and function of the integrated coupling element are tested using two numerical examples. The influences of different combinations of rail and bridge element length in the coupling element on the solution are investigated, and the effects of different rail irregularities on the dynamic responses are discussed.展开更多
The binding energy spectrum and electron momentum distributions for the outer valence orbitals of n-propyl iodide molecule have been measured using the electron momentum spectrometer employing non-coplanar asymmetric ...The binding energy spectrum and electron momentum distributions for the outer valence orbitals of n-propyl iodide molecule have been measured using the electron momentum spectrometer employing non-coplanar asymmetric geometry at impact energy of 2.5 keV plus binding energy. The ionization bands have been assigned in detail via the high accuracy SACCI general-R method calculation and the experimental momentum profiles are compared with the theoretical ones calculated by Hartree-Fock and B3LYP/aug-cc-pVTZ（C,H）6-311G？？（I）. The spin-orbit coupling effect and intramolecular orbital interaction have been analyzed for the outermost two bands, which are assigned to the iodine 5p lone pairs, using NBO method and non-relativistic as well as relativistic calculations. It is found that both of the interactions will lead to the observed differences in electron momentum distributions. The experimental results agree with the relativistic theoretical momentum profiles, indicating that the spin-orbit coupling effect dominates in n-propyl iodide molecule.展开更多
The influence of annealing time on the magnetic properties and microstructure of nanocomposite Pr7.5Dy1Fe71Co15Nb1B4.5 ribbons was systematically investigated by the methods of vibrating sample magnetometer （VSM）, ...The influence of annealing time on the magnetic properties and microstructure of nanocomposite Pr7.5Dy1Fe71Co15Nb1B4.5 ribbons was systematically investigated by the methods of vibrating sample magnetometer （VSM）, X-ray diffraction （XRD） and high resolution transmission electron microscopy （HRTEM）. Interaction domains derived from strong exchange coupling interactions between hard and soft magnetic grains were imaged using magnetic force microscopy （MFM）. Maximum remanence, intrinsic coercivity, and maximum energy product values were obtained in the ribbons annealed at 700℃ for 15 min, which were composed of Pr2（Fe, Co）14B, α-（Fe, Co）, and slight Pr2（Fe, CO）17 phases. Although Jr, Hci, and （Bn）max decreased gradually with further increase of annealing time, it is emphasized that comparatively high Jr and Hci and （BH）max were obtained in a wide annealing time period of 15 to 360 min. The shape of initial magnetization curves and hysteresis loops change as a function of annealing time, indicating different magnetization reversal routes, which can be fully explained by the corresponding microstructure.展开更多
An integrated fluid-thermal-structural analysis approach is presented. In this approach, the heat conduction in a solid is coupled with the heat convection in the viscous flow of the fluid resulting in the thermal str...An integrated fluid-thermal-structural analysis approach is presented. In this approach, the heat conduction in a solid is coupled with the heat convection in the viscous flow of the fluid resulting in the thermal stress in the solid. The fractional four-step finite element method and the streamline upwind Petrov-Galerkin （SUPG） method are used to analyze the viscous thermal flow in the fluid. Analyses of the heat transfer and the thermal stress in the solid axe performed by the Galerkin method. The second-order semi- implicit Crank-Nicolson scheme is used for the time integration. The resulting nonlinear equations are lineaxized to improve the computational efficiency. The integrated analysis method uses a three-node triangular element with equal-order interpolation functions for the fluid velocity components, the pressure, the temperature, and the solid displacements to simplify the overall finite element formulation. The main advantage of the present method is to consistently couple the heat transfer along the fluid-solid interface. Results of several tested problems show effectiveness of the present finite element method, which provides insight into the integrated fluid-thermal-structural interaction phenomena.展开更多
The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more ...The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more complex than that of a single pipe.However,there are few reports about the dynamic characteristics of the PLFPs.Therefore,this paper proposes improved frequency modeling and solution for the PLFPs,involving the logical alignment principle and coupled matrix processing.The established model incorporates both the fluid-structure interaction(FSI)and the structural coupling of the PLFPs.The validity of the established model is verified by modal experiments.The effects of some unique parameters on the dynamic characteristics of the PLFPs are discussed.This work provides a feasible method for solving the FSI of multiple pipes in parallel and potential theoretical guidance for the dynamic analysis of the PLFPs in engineering.展开更多
The coupling interaction between an individual optical emitter and the propagating surface plasmon polaritons in a graphene microribbon （GMR） waveguide is investigated by numerical calculations, where the emitter is...The coupling interaction between an individual optical emitter and the propagating surface plasmon polaritons in a graphene microribbon （GMR） waveguide is investigated by numerical calculations, where the emitter is situated above the GMR or in the same plane of the GMR, The results reveal a multimode coupling mechanism for the strong interaction between the emitter and the propagating plasmonic waves in graphene. When the emitter is situated in the same plane of the GMR, the decay rate from the emitter to the surface plasmon polaritons increases more than 10 times compared with that in the case with the emitter above the GMR.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.42272153 and 42472195)the Research Fund of PetroChina Tarim Oilfield Company(No.671023060003)the Research Fund of China National Petroleum Corporation Limited(No.2023ZZ16YJ04).
文摘Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression and permeability tests to investigate the mechanical and seepage properties of tight sandstone.A digital core of tight sandstone was built using Computed Tomography(CT)scanning,which was divided into matrix and pore phases by a pore equivalent diameter threshold.A fluid-solid coupling model was established to investigate the seepage characteristics at micro-scale.The results showed that increasing the confining pressure decreased porosity,permeability,and flow velocity,with the pore phase becoming the dominant seepage channel.Cracks and large pores closed first under increasing pressure,resulted in a steep drop in permeability.However,permeability slightly decreased under high confining pressure,which followed a first-order exponential function.Flow velocity increased with seepage pressure.And the damage mainly occurred in stress-concentration regions under low seepage pressure.Seepage behavior followed linear Darcy flow,the damage emerged at seepage entrances under high pressure,which decreased rock elastic modulus and significantly increased permeability.
基金supported by the National Natural Science Foundation of China(Grant No.52374079)Chongqing Graduate Research Innovation Project(Grant No.CYB22032)Chongqing Talents and Outstanding Scientists Project(Grant No.cstc2024ycjhbgzxm0032).
文摘Deep underground excavation causes considerable unloading effects,leading to a pronounced bias pressure phenomenon.The deformation and seepage characteristics of rock masses under different gas and confining pressures were investigated via triaxial loading and unloading seepage tests.When the influential coefficient of effective confining pressure(β)is less than 0.065,the seepage force considerably weakens the strength of fractured rock masses.Conversely,whenβis greater than 0.065,the opposite is true.Moreover,the increase in the axial load leads to an increase in the precast fracture volumetric strain,which is the main reason for the increase in fracture permeability.This effect is particularly significant during the unloading stage.Based on the test results,a method for calculating the dynamic seepage evolution of rock masses,considering the effects of rock mass damage and fracture deformation,is introduced,and the effectiveness of the calculation is validated.The entire description of the seepage under loading and unloading was accomplished.The equivalent relationship between the lateral and normal stresses on fracture surfaces ranges from 0.001 to 0.1,showing an exponential variation between the lateral stress influence coefficient on normal deformation(χ)and seepage pressure.Before the failure of the rock mass,the seepage in the fractures was in a linear laminar flow state.However,after the failure,when the gas pressure reached 2 MPa,the flow state in the fractures transitioned to nonlinear laminar flow.The results are important for predicting hazardous gas leaks during deep underground engineering excavation.
基金financially supported by the National Key Research and Development Plan(2023YFC2811001)the National Natural Science Foundation of China(42206233)the Taishan Scholars Program(tsqn202312280,tsqn202306297)。
文摘Hydraulic fracturing technology has played an important role in the exploitation of unconventional oil and gas resources,however,its application to gas hydrate reservoirs has been rarely studied.Currently,there is still limited understanding of the propagation and extension of fractures around the wellbore during the fracturing process of horizontal wells in hydrate reservoirs,as well as the stress interference patterns between fractures.This study simulates hydraulic fracturing processes in hydrate reservoirs using a fluidsolid coupling discrete element method(DEM),and analyzes the impacts of hydrate saturation and geological and engineering factors on fracture extension and stress disturbance.The results show that hydraulic fracturing is more effective when hydrate saturation exceeds 30%and that fracture pressure increases with saturation.The increase in horizontal stress differential enhances the directionality of fracture propagation and reduces stress disturbance.The distribution uniformity index(DUI)reveals that injection pressure is directly proportional to the number of main fractures and inversely proportional to fracturing time,with fracturing efficiency depending on the spacing between injection points and the distance between wells.This work may provide reference for the commercial exploitation of natural gas hydrates.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1604200)the National Natural Science Foundation of China(Grant No.12261131495)Institute of Systems Science,Beijing Wuzi University(Grant No.BWUISS21).
文摘The coupled nonlocal nonlinear Schrödinger equations with variable coefficients are researched using the nonstandard Hirota bilinear method.The two-soliton and double-hump one-soliton solutions for the equations are first obtained.By assigning different functions to the variable coefficients,we obtain V-shaped,Y-shaped,wave-type,exponential solitons,and so on.Next,we reveal the influence of the real and imaginary parts of the wave numbers on the double-hump structure based on the soliton solutions.Finally,by setting different wave numbers,we can change the distance and transmission direction of the solitons to analyze their dynamic behavior during collisions.This study establishes a theoretical framework for controlling the dynamics of optical fiber in nonlocal nonlinear systems.
基金supported by the National Natural Science Foundation of China(Nos.U20A20111,41977229)the Sichuan Youth Science and Technology Innovation Research Team Project(No.2020JDTD0006).
文摘In the context of global warming and intensified human activities,glacier instability in plateau regions has increased,and glacier debris flows have become active,which poses a significant threat to the lives and property of people and socioeconomic development.The mass movement process of glacier debris flows is extremely complex,so this paper uses the 2018 Sedongpu glacier debris flow event on the Qinghai-Tibet Plateau as an example and applies a numerical simulation method to invert the whole process of mass movement.In view of the interaction between phases in the process of motion,we use the fluid-solid coupling method to describe the mass movement.The granular-flow model and drift-flux model are employed in FLOW3D software to study the mass movement process of glacier debris flows and explore their dynamic characteristics.The results indicate that the glacier debris flow lasted for 700 s,and the movement process was roughly divided into four stages,including initiation,scraping,surging and deposition;the depositional characteristics calculated by the fluid-solid coupling model are consistent with the actual survey results and have good reliability;strong erosion occurs during the mass movement,the clear volume amplification effect,and the first wave climbs 17.8 m across the slope.The fluid-solid coupling method can better simulate glacier debris flows in plateau regions,which is helpful for the study of the mechanism and dynamic characteristics of such disasters.
文摘This paper introduces MultiPHydro,an in-house computational solver developed for simulating hydrodynamic and multiphase fluid—body interaction problems,with a specialized focus on multiphase flow dynamics.The solver employs the boundary data immersion method(BDIM)as its core numerical framework for handling fluid—solid interfaces.We briefly outline the governing equations and physical models integrated within MultiPHydro,including weakly-compressible flows,cavitation modeling,and the volume of fluid(VOF)method with piecewise-linear interface reconstruction.The solver’s accuracy and versatility are demonstrated through several numerical benchmarks:single-phase flow past a cylinder shows less than 10%error in vortex shedding frequency and under 4%error in hydrodynamic resistance;cavitating flows around a hydrofoil yield errors below 7%in maximum cavity length;water-entry cases exhibit under 5%error in displacement and velocity;and water-exit simulations predict cavity length within 7.2%deviation.These results confirm the solver’s capability to reliably model complex fluid-body interactions across various regimes.Future developments will focus on refining mathematical models,improving the modeling of phase-interaction mechanisms,and implementing GPU-accelerated parallel algorithms to enhance compatibility with domestically-developed operating systems and deep computing units(DCUs).
基金Supported by Open Fund of Engineering Research Center of Ministry of Education for Wetland Ecology and Agricultural Utilization(KF202015).
文摘In this paper,the vegetable field in the teaching base of College of Agriculture,Yangtze University was taken as the research object.The indoor simulation method was used to explore the effects of temperature and moisture on the phosphorus(P)bioavailability of vegetable soil.Three temperature gradients[T1(15℃),T2(25℃),T3(35℃)]and three humidity gradients[W1(40%),W2(70%),W3(100%)]were set in the test.The results showed that it could improve the contents of HCl-P,Enzyme-P,Citrate-P,and Olsen-P in vegetable soil by increasing soil moisture content;temperature rise was helpful to increase the contents of HCl-P and Olsen-P,but it could reduce the content of Citrate-P.The contents of Enzyme-P and CaCl 2-P were significantly affected by hydrothermal interaction.Within a certain range of soil temperature and humidity,temperature and moisture had a positive coupling effect on soil P bioavailability components,and significantly affected soil P supply capacity.
基金This work was supported by the National Natural Science Foundation of China(Grant No.12172160)Shenzhen Science and Technology Program(Grant No.JCYJ20220818100600002)+1 种基金South-ern University of Science and Technology(Grant No.Y01326127)the Department of Science and Technology of Guangdong Province(Grant Nos.2020B1212030001 and 2021QN020642).
文摘We propose a suite of strategies for the parallel solution of fully implicit monolithic fluid-structure interaction(FSI).The solver is based on a modeling approach that uses the velocity and pressure as the primitive variables,which offers a bridge between computational fluid dynamics(CFD)and computational structural dynamics.The spatiotemporal discretization leverages the variational multiscale formulation and the generalized-αmethod as a means of providing a robust discrete scheme.In particular,the time integration scheme does not suffer from the overshoot phenomenon and optimally dissipates high-frequency spurious modes in both subproblems of FSI.Based on the chosen fully implicit scheme,we systematically develop a combined suite of nonlinear and linear solver strategies.Invoking a block factorization of the Jacobian matrix,the Newton-Raphson procedure is reduced to solving two smaller linear systems in the multi-corrector stage.The first is of the elliptic type,indicating that the algebraic multigrid method serves as a well-suited option.The second exhibits a two-by-two block structure that is analogous to the system arising in CFD.Inspired by prior studies,the additive Schwarz domain decomposition method and the block-factorization-based preconditioners are invoked to address the linear problem.Since the number of unknowns matches in both subdomains,it is straightforward to balance loads when parallelizing the algorithm for distributed-memory architectures.We use two representative FSI benchmarks to demonstrate the robustness,efficiency,and scalability of the overall FSI solver framework.In particular,it is found that the developed FSI solver is comparable to the CFD solver in several aspects,including fixed-size and isogranular scalability as well as robustness.
基金the National Natural Science Foundation of China(92261203,22101116,21971106)the Science Research Foun dation of jilin Province(YDZJ202301ZYTS478)。
文摘Manipulating magnetic couplings in molecular magnets is of great importance in improving the mag-netic properties of such materials.It has been proved that by adjusting the strength of magnetic cou-plings and the arrangement of the intermolecular magnetic dipoles,magnetic blocking can be significantly enhanced.Herein manipulating the intramolecular dipole interactions by ligand modifica-tion was attempted with the use of three closely related dinuclear Er(Ⅲ)complexes of a common chemical formula of[(COT^(R))Er(μ-CI)(THF)]_(2)(COT^(R)is monosubstituted cyclooctatetraenide dianions with R=diphenylmethylsilyl(Ph_(2)MeS)for 1,triethylsilyl(TES)for 2,and triisopropylsilyl(TIPS)for 3).Each of these complexes features a centrosymmetric dinuclear core unit with their component Er(Ⅲ)ions doubly bridged by two chloro ligands and further coordinated with a capping substituted corR ligand and a coordinated THF molecule.Magnetic studies reveal that the complexes display similar ferromagnetic couplings with comparable single-molecule magnetic behaviors.The ferromagnetic couplings dominated by the intramolecular dipole interactions are found to be 0.7614,0.7380,and 0.5635 cm^(-1)for 1,2,and 3,respectively.The angles(θ)between the magnetic easy axes and the intramolecular Er-Er lines are 24.88(2)°,25.23(1),and 31.85(5),leading to transversal dipole fields of 0.0114,0.0113,and 0.0125 T for 1,2,and 3,respectively.Although the different ligand substitution generates a sizable difference of about 7 in theθangle,the resulting difference in the dipole interactions is not sufficiently strong to cause any significant differences in their magnetic properties.Further change in theθangles to the"side-by-side"(θ=90°)or"head-to-tail"(θ=0°)arrangement of the magnetic easy axes,achievable by rational mo-lecular design,is expected to lead to molecular magnetic materials with much enhanced properties.
基金supported by the National Natural Science Foundation of China(Grant Nos.12204173 and 12275263)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301900)supported by the Natural Science Foundation of Fujian Province 802 of China(Grant No.2023J02032)。
文摘The crossover between short-range and long-range(LR)universal behaviors remains a central theme in the physics of LR interacting systems.The competition between LR coupling and the Berezinskii-Kosterlitz-Thouless mechanism makes the problem more subtle and less understood in the two-dimensional(2D)XY model,a cornerstone for investigating low-dimensional phenomena and their implications in quantum computation.We study the 2D XY model with algebraically decaying interaction~1/r^(2+σ).Utilizing an advanced update strategy,we conduct LR Monte Carlo simulations of the model up to a linear size of L=8192.Our results demonstrate continuous phase transitions into a ferromagnetic phase forσ<2,which exhibit the simultaneous emergence of a long-ranged order and a power-law decaying correlation function due to the Goldstone mode.Furthermore,we fnd logarithmic scaling behaviors in the low-temperature phase atσ=2.The observed scaling behaviors in the low-temperature phase forσ≤2 agree with our theoretical analysis.Our fndings request further theoretical understanding and can be of practical application in cutting-edge experiments like Rydberg atom arrays.
基金financially supported by the National Key Research and Development Program of China-Young Scientist Project(No.2024YFC2815400)the National Natural Science Foundation of China(No.52588202).
文摘Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineering challenges.This study establishes a multiscale modelling framework coupling the discrete element method(DEM)with multi-body dynamics(MBD)to investigate track-seabed dynamic interactions across three operational modes:flat terrain,slope climbing,and ditch surmounting.The simulation framework,validated against laboratory experiments,systematically evaluates the influence of grouser geometry(involute,triangular,and pin-type)and traveling speed(0.2–1.0 m/s)on traction performance,slip rate,and ground pressure distribution.Results reveal rate-dependent traction mechanisms governed by soil microstructural responses:higher speeds enhance peak traction but exacerbate slip instability on complex terrain.Critical operational thresholds are established—0.7 m/s for flat terrain,≤0.5 m/s for slopes and ditches—with distinct grouser optimization strategies:involute grousers achieve 35%–40%slip reduction on slopes through progressive soil engagement,while triangular grousers provide optimal impact resistance during ditch crossing with 30%–35%performance improvement.These findings provide quantitative design criteria and operational guidelines for optimizing TMV structural parameters and control strategies,offering a robust theoretical foundation for enhancing the performance,safety,and reliability of deep-sea mining equipment in complex submarine environments.
基金supported by the National Natural Science Foundation of China(Nos.U24B6002,42488101)the Key R&D Program of Shandong Province,China(No.2024CXPT076)the Independent innovation research program of China University of Petroleum(East China)(No.21CX06001A)。
文摘0 INTRODUCTION Pressure-stress coupling(PSC)refers to the bidirectional mechanical interaction between pore pressure and in-situ stress within subsurface formations(Hillis,2000).Variations in pore pressure redistribute the stress field,while evolving stress states in turn alter pore pressure.This reciprocity,governed by poroelasticity and multiphysics interactions,underlies a wide spectrum of geomechanical processes,including fracture initiation,fluid migration,reservoir evolution,and fault slip or seismicity(Xu et al.,2020).Conventional theories often treat pressure and stress as independent variables.
基金supported in part by R & D Department of China National Petroleum Corporation (2022DQ0604-01)National Natural Science Foundation of China (42204132)+3 种基金the China Postdoctoral Science Foundations (2020M680667, 2021T140661)Harvard-CUP Joint Laboratory on Petroleum Science“111” project (B13010)the financial support from the CAS Special Research Assistant Project。
文摘Seismic wave propagation in fluid-solid coupled media is currently a popular topic. However, traditional wave equation-based simulation methods have to consider complex boundary conditions at the fluid-solid interface. To address this challenge, we propose a novel numerical scheme that integrates the lattice Boltzmann method(LBM) and lattice spring model(LSM). In this scheme, LBM simulates viscoacoustic wave propagation in the fluid area and LSM simulates elastic wave propagation in the solid area. We also introduce three different LBM-LSM coupling strategies, a standard bounce back scheme, a specular reflection scheme, and a hybrid scheme, to describe wave propagation across fluid-solid boundaries. To demonstrate the accuracy of these LBM-LSM coupling schemes, we simulate wave propagation in a two-layer model containing a fluid-solid interface. We place excitation sources in the fluid layer and the solid layer respectively, to observe the wave phenomena when seismic waves propagate to interface from different sides. The simulated results by LBM-LSM are compared with the reference wavefields obtained by the finite difference method(FDM) and the analytical solution(ANA).Our LBM-LSM coupling scheme was verified effective, as the relative errors between the LBM-LSM solutions and reference solutions were within an acceptable range, sometimes around 1.00%. The coupled LBM-LSM scheme is further used to model seismic wavefields across a more realistic rugged seabed,which reveals the potential applications of the coupled LBM-LSM scheme in marine seismic imaging techniques, such as reverse-time migration and full-waveform inversion. The method also has potential applications in simulating wave propagation in complex two-and multi-phase media.
基金Project supported by the National Natural Science Foundation of China(No.51078164)
文摘An integrated coupling element considering wheel-rail interface for analyzing the dynamic responses of vehicle-rail-bridge interaction system with a non-uniform continuous bridge is presented. The governing equations of the interaction system are established first, and the solution procedure and assembly method of the coupling element are demonstrated. Finally, the accuracy, efficiency and function of the integrated coupling element are tested using two numerical examples. The influences of different combinations of rail and bridge element length in the coupling element on the solution are investigated, and the effects of different rail irregularities on the dynamic responses are discussed.
文摘The binding energy spectrum and electron momentum distributions for the outer valence orbitals of n-propyl iodide molecule have been measured using the electron momentum spectrometer employing non-coplanar asymmetric geometry at impact energy of 2.5 keV plus binding energy. The ionization bands have been assigned in detail via the high accuracy SACCI general-R method calculation and the experimental momentum profiles are compared with the theoretical ones calculated by Hartree-Fock and B3LYP/aug-cc-pVTZ（C,H）6-311G？？（I）. The spin-orbit coupling effect and intramolecular orbital interaction have been analyzed for the outermost two bands, which are assigned to the iodine 5p lone pairs, using NBO method and non-relativistic as well as relativistic calculations. It is found that both of the interactions will lead to the observed differences in electron momentum distributions. The experimental results agree with the relativistic theoretical momentum profiles, indicating that the spin-orbit coupling effect dominates in n-propyl iodide molecule.
基金This work was financially supported by the National Natural Science Foundation of China (No.10074005)
文摘The influence of annealing time on the magnetic properties and microstructure of nanocomposite Pr7.5Dy1Fe71Co15Nb1B4.5 ribbons was systematically investigated by the methods of vibrating sample magnetometer （VSM）, X-ray diffraction （XRD） and high resolution transmission electron microscopy （HRTEM）. Interaction domains derived from strong exchange coupling interactions between hard and soft magnetic grains were imaged using magnetic force microscopy （MFM）. Maximum remanence, intrinsic coercivity, and maximum energy product values were obtained in the ribbons annealed at 700℃ for 15 min, which were composed of Pr2（Fe, Co）14B, α-（Fe, Co）, and slight Pr2（Fe, CO）17 phases. Although Jr, Hci, and （Bn）max decreased gradually with further increase of annealing time, it is emphasized that comparatively high Jr and Hci and （BH）max were obtained in a wide annealing time period of 15 to 360 min. The shape of initial magnetization curves and hysteresis loops change as a function of annealing time, indicating different magnetization reversal routes, which can be fully explained by the corresponding microstructure.
基金the National Metal and Materials Technology Centerthe Thailand Research Fund+1 种基金the Office of Higher Education Commissionthe Chulalongkorn University for supporting the present research
文摘An integrated fluid-thermal-structural analysis approach is presented. In this approach, the heat conduction in a solid is coupled with the heat convection in the viscous flow of the fluid resulting in the thermal stress in the solid. The fractional four-step finite element method and the streamline upwind Petrov-Galerkin （SUPG） method are used to analyze the viscous thermal flow in the fluid. Analyses of the heat transfer and the thermal stress in the solid axe performed by the Galerkin method. The second-order semi- implicit Crank-Nicolson scheme is used for the time integration. The resulting nonlinear equations are lineaxized to improve the computational efficiency. The integrated analysis method uses a three-node triangular element with equal-order interpolation functions for the fluid velocity components, the pressure, the temperature, and the solid displacements to simplify the overall finite element formulation. The main advantage of the present method is to consistently couple the heat transfer along the fluid-solid interface. Results of several tested problems show effectiveness of the present finite element method, which provides insight into the integrated fluid-thermal-structural interaction phenomena.
基金Project supported by the National Natural Science Foundation of China(No.11972112)the Fundamental Research Funds for the Central Universities of China(Nos.N2103024 and N2103002)the Major Projects of Aero-Engines and Gasturbines(No.J2019-I-0008-0008)。
文摘The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more complex than that of a single pipe.However,there are few reports about the dynamic characteristics of the PLFPs.Therefore,this paper proposes improved frequency modeling and solution for the PLFPs,involving the logical alignment principle and coupled matrix processing.The established model incorporates both the fluid-structure interaction(FSI)and the structural coupling of the PLFPs.The validity of the established model is verified by modal experiments.The effects of some unique parameters on the dynamic characteristics of the PLFPs are discussed.This work provides a feasible method for solving the FSI of multiple pipes in parallel and potential theoretical guidance for the dynamic analysis of the PLFPs in engineering.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51172030,11274052,51102019,51172208,and 61274015)the National Basic Research Program of China(Grant No.2010CB923200)
文摘The coupling interaction between an individual optical emitter and the propagating surface plasmon polaritons in a graphene microribbon （GMR） waveguide is investigated by numerical calculations, where the emitter is situated above the GMR or in the same plane of the GMR, The results reveal a multimode coupling mechanism for the strong interaction between the emitter and the propagating plasmonic waves in graphene. When the emitter is situated in the same plane of the GMR, the decay rate from the emitter to the surface plasmon polaritons increases more than 10 times compared with that in the case with the emitter above the GMR.
