Oil shale is characterized by a dense structure,low proportion of pores and fissures,and low permeability.Pore-fracture systems serve as crucial channels for shale oil migration,directly influencing the production eff...Oil shale is characterized by a dense structure,low proportion of pores and fissures,and low permeability.Pore-fracture systems serve as crucial channels for shale oil migration,directly influencing the production efficiency of shale oil resources.Effectively stimulating oil shale reservoirs remains a challenging and active research topic.This investigation employed shale specimens obtained from the Longmaxi Formation.Scanning electron microscopy,fluid injection experiments,and fluid-structure interaction simulations were used to comprehensively analyze structural changes and fluid flow behavior under high temperatures from microscopic to macroscopic scales.Experimental results indicate that the temperature has little effect on the structure and permeability of shale before 300℃.However,there are two threshold temperatures within the range of 300 to 600℃that have significant effects on the structure and permeability of oil shale.The first threshold temperature is between 300 and 400℃,which causes the oil shale porosity,pore-fracture ratio,and permeability begin to increase.This is manifested by the decrease in micropores and mesopores,the increase in macropores,and the formation of a large number of isolated pores and fissures within the shale.The permeability increases but not significantly.The second threshold temperature is between 500 and 600℃,which increases the permeability of oil shale significantly.During this stage,micropores and mesopores are further reduced,and macropores are significantly enlarged.A large number of connected and penetrated pores and fissures are formed.More numerous and thicker streamlines appear inside the oil shale.The experimental results demonstrate that high temperatures significantly alter the microstructure and permeability of oil shale.At the same time,the experimental results can provide a reference for the research of in-situ heating techniques in oil shale reservoir transformation.展开更多
The closely coupled approach combined with the finite volume method （FVM） solver and the finite element method （FEM） solver is used to investigate the fluid-structure interaction （FSI） of a three-dimensional can...The closely coupled approach combined with the finite volume method （FVM） solver and the finite element method （FEM） solver is used to investigate the fluid-structure interaction （FSI） of a three-dimensional cantilevered hydrofoil in the water tunnel. The FVM solver and the coupled approach are verified and validated by compar- ing the numerical predictions with the experimental measurements, and good agreement is obtained concerning both the lift on the foil and the tip displacement. In the noncav- itating flow, the result indicates that the growth of the initial incidence angle and the Reynolds number improves the deformation of the foil, and the lift on the foil is increased by the twist deformation. The normalized twist angle and displacement along the span of the hydrofoil for different incidence angles and Reynolds numbers are almost uniform. For the cavitation flow, it is shown that the small amplitude vibration of the foil has limited influence on the developing process of the partial cavity, and the quasi two-dimensional cavity shedding does not change the deformation mode of the hydrofoil. However, the frequency spectrum of the lift on the foil contains the frequency which is associated with the first bend frequency of the hydrofoil.展开更多
Elevated intraocular pressure appears to have a broader impact on increased resistance to aqueous humor outflow through the conventional aqueous outflow system(AOS).However,there is still no consensus about exact loca...Elevated intraocular pressure appears to have a broader impact on increased resistance to aqueous humor outflow through the conventional aqueous outflow system(AOS).However,there is still no consensus about exact location of the increased outflow resistance of aqueous humor,and the mechanism is not perfect.In addition,it is difficult to accurately obtain hydrodynamic parameters of aqueous humor within the trabecular meshwork outflow pathways based on the current technology.In this paper,a two-way fluid-structure interaction simulation was performed to study the pressure difference and velocity in the superficial trabecular meshwork,juxtacanalicular meshwork(JCM)and Schlemm’s canal in response to JCM permeability changes.We obtained the JCM permeability of normal intraocular pressure varied between 1×10?15 m2 and 10×10?15 m2 while permeability of the JCM ranged from 2×10?16 m2 and 3×10?16 m2 under conditions of high intraocular pressure.The study indicated that the fluid dynamics parameters in trabecular meshwork and Schlemm’s canal are most significantly affected by the changes of JCM permeability.Moreover,the study demonstrates that the finite element modeling of AOS provides a practical means for studying the outflow dynamics and the biomechanical environment of the AOS.展开更多
The multi-body flexible morphing airfoil can improve the aerodynamic characteristics based on different flight missions continuously.Recently researches have focused on the unsteady aerodynamic characteristics of flex...The multi-body flexible morphing airfoil can improve the aerodynamic characteristics based on different flight missions continuously.Recently researches have focused on the unsteady aerodynamic characteristics of flexible wings under passive actuation.However,the unsteady aerodynamic characteristics with the fluid-structure interaction effects in the multi-body active actuation process of morphing airfoil deserve further investigation.In this paper,a fluid-structure coupled simulation method for multi-body flexible morphing airfoil with active actuation subsystem was investigated,and the aerodynamic characteristics during deformation were compared with different skin flexibility,flow field environment,actuation mode and actuation time.The numerical results show that for the steady aerodynamic,the skin flexibility can improve the stability efficiency.In the unsteady process,the change trend of the transient lift coefficient and pitching moment are consistent with those of the active drive characteristics,while the instantaneous lift-drag ratio coefficient is greatly affected by the driving mode and can be improved by increasing the driving duration.展开更多
Based on the theories of the gas seepage in coal seams and the deformation of the coal-rock medium,the gas seepage field in coal-rock mass is coupled with the deformation field of the coal-rock mass to establish a flu...Based on the theories of the gas seepage in coal seams and the deformation of the coal-rock medium,the gas seepage field in coal-rock mass is coupled with the deformation field of the coal-rock mass to establish a fluidstructure interaction model for the interaction between coal gas and coal-rock masses.The outburst process in coal-rock masses under the joint action of gas pressure and crustal stress is simulated using the material point method.The simulation results show the changes in gas pressure,velocity distribution,maximum principal stress distribution,and damage distribution during the process of the coal and gas outburst,as well as themovement and accumulation of coal-rock masses after the occurrence of the outburst.It was found that the gas pressure gradient was greatest at theworking face after the occurrence of the outburst,the gas pressures and pressure gradients at each location within the coal seamgradually decreased with time,and the damage distribution was essentially the same as the minimum principal stress distribution.The simulation further revealed that the outburst first occurred in themiddle of the tunnel excavation face and that the speed at which particles of coal mass were ejected was highest at the center and decreased toward the upper and lower sides.The study provides a scientific basis for enhancing our understanding of the mechanism behind coal and gas outbursts,as well as their prevention and control.展开更多
In order to improve the efficiency of heart valve simulation,we proposed a fast isogeometric simulation approach for time-dependent heart valve simulation algorithm with the idea of Geometric-Independent Field approxi...In order to improve the efficiency of heart valve simulation,we proposed a fast isogeometric simulation approach for time-dependent heart valve simulation algorithm with the idea of Geometric-Independent Field approximation(GIFT for short).For the solution of the blood flow field problem in a heart valve,the fluid background mesh is first simplified,then a Bézier tetrahedral mesh is generated based on the simplified mesh to maintain geometric precision,and finally,the fluid velocity field and pressure are solved.In addition,the GIFT idea is used to represent the geometry of computational domain geometry and approximate the physical field solution with different basis function spaces to obtain the numerical solution with the same precision as before simplification.In the structural mechanics simulation of valve leaflets,NURBS surfaces are used to represent the geometric model.To avoid degeneration on geometric boundary,a single leaflet geometric patch is subdivided into four patches.The immersion geometry strategy is adopted in solving the deformation problem of cardiac valve leaflets to achieve high simulation precision,and the dynamic augmented Lagrangian algorithm is used to couple fluid-structure control equations.For the time discretization,the generalizedαmethod is used to control high-frequency dissipation.Numerical examples and comparisons with previous methods are also presented.The proposed algorithm can reduce the computing costs by about 54.3%,which proves the effectiveness of the proposed method.展开更多
In this paper, the authors present airflow field characteristics of human upper airway and soft palate movement attitude during breathing. On the basis of the data taken from the spiral computerized tomography images ...In this paper, the authors present airflow field characteristics of human upper airway and soft palate movement attitude during breathing. On the basis of the data taken from the spiral computerized tomography images of a healthy person and a patient with Obstructive Sleep Apnea-Hypopnea Syndrome （OSAHS）, three-dimensional models of upper airway cavity and soft palate are reconstructed by the method of surface rendering. Numerical simulation is performed for airflow in the upper airway and displacement of soft palate by fluid-structure interaction analysis. The reconstructed threedimensional models precisely preserve the original configuration of upper airways and soft palate. The results of the pressure and velocity distributions in the airflow field are quantitatively determined, and the displacement of soft palate is presented. Pressure gradients of airway are lower for the healthy person and the airflow distribution is quite uniform in the case of free breathing. However, the OSAHS patient remarkably escalates both the pressure and velocity in the upper airway, and causes higher displacement of the soft palate. The present study is useful in revealing pathogenesis and quantitative mutual relationship between configuration and function of the upper airway as well as in diagnosingdiseases related to anatomical structure and function of the upper airway.展开更多
An effective computational method is developed for dynamic analysis offluid-structure interaction problems involving large-amplitude sloshing of the fluid andlarge-displacement motion of the structure. The structure i...An effective computational method is developed for dynamic analysis offluid-structure interaction problems involving large-amplitude sloshing of the fluid andlarge-displacement motion of the structure. The structure is modeled as a rigid container supportedby a system consisting of springs and dashpots. The motion of the fluid is decomposed into twoparts: the large-displacement motion with the container and the large-amplitude sloshing relative tothe container. The former is conveniently dealt with by defining a container-fixed noninertiallocal frame, while the latter is easily handled by adopting an ALE kinematical description. Thisleads to an easy and accurate treatment of both the fluid-structure interface and the fluid freesurface without producing excessive distortion of the computational mesh. The coupling between thefluid and the structure is accomplished through the coupling matrices that can be easilyestablished. Two numerical examples, including a TLD-structure system and a simplified liquid-loadedvehicle system, are presented to demonstrate the effectiveness and reliability of the proposedmethod. The present work can also be applied to simulate fluid-structure problems incorporatingmultibody systems and several fluid domains.展开更多
In the underwater-shock environment, cavitation occurs near the structural surface. The dynamic response of fluid-structure interactions is influenced seriously by the cavitation effects. It is also the difficulty in ...In the underwater-shock environment, cavitation occurs near the structural surface. The dynamic response of fluid-structure interactions is influenced seriously by the cavitation effects. It is also the difficulty in the field of underwater explosion. With the traditional boundary element method and the finite element method （FEM）, it is difficult to solve the nonlinear problem with cavitation effects subjected to the underwater explosion. To solve this problem, under the consideration of the cavitation effects and fluid compressibility, with fluid viscidity being neglected, a 3D numerical model of transient nonlinear fluid-structure interaction subjected to the underwater explosion is built. The fluid spectral element method （SEM） and the FEM are adopted to solve this model. After comparison with the FEM, it is shown that the SEM is more precise than the FEM, and the SEM results are in good coincidence with benchmark results and experiment results. Based on this, combined with ABAQUS, the transient fluid-structure interaction mechanism of the 3D submerged spherical shell and ship stiffened plates subjected to the underwater explosion is discussed, and the cavitation region and its influence on the structural dynamic responses are presented. The paper aims at providing references for relevant research on transient fluid-structure interaction of ship structures subjected to the underwater explosion.展开更多
This article introduces a numerical scheme on the basis of semi-implicit method for pressure-linked equations （SIMPLE） algorithm to simulate incompressible unsteady flows with fluid-structure interaction. The Navier...This article introduces a numerical scheme on the basis of semi-implicit method for pressure-linked equations （SIMPLE） algorithm to simulate incompressible unsteady flows with fluid-structure interaction. The Navier-Stokes equation is discretized spatially with collocated finite volume method and Eulerian implicit method in time domain. The hybrid method that combines immersed boundary method （IBM） and volume of fluid （VOF） method is used to deal with rigid body motion in fluid domain. The details of movement of immersed boundary （IB） and calculation of VOF are also described. This method can be easily applied to any existing finite-volume-based computational fluid dynamics （CFD） solver without complex operation, with which fluid flow interaction of arbitrarily complex geometry can be realized on a fixed mesh. The method is verified by low Reynolds number flows passing both stationary and oscillating cylinders. The drag and lift coefficients acquired by the study well accord with other published results, which indicate the reasonability of the proposed method.展开更多
Fluid-structure interaction （FSI） problems in microchannels play a prominent role in many engineering applications. The present study is an effort toward the simulation of flow in microchannel considering FSI. The b...Fluid-structure interaction （FSI） problems in microchannels play a prominent role in many engineering applications. The present study is an effort toward the simulation of flow in microchannel considering FSI. The bottom boundary of the microchannel is simulated by size-dependent beam elements for the finite element method （FEM） based on a modified cou- ple stress theory. The lattice Boltzmann method （LBM） using the D2Q13 LB model is coupled to the FEM in order to solve the fluid part of the FSI problem. Because of the fact that the LBM generally needs only nearest neighbor information, the algorithm is an ideal candidate for parallel computing. The simulations are carried out on graphics processing units （GPUs） using computed unified device architecture （CUDA）. In the present study, the governing equations are non-dimensionalized and the set of dimensionless groups is exhibited to show their effects on micro-beam displacement. The numerical results show that the displacements of the micro-beam predicted by the size-dependent beam element are smaller than those by the classical beam element.展开更多
In order to simulate and analyze the dynamic characteristics of the parachute from advanced tactical parachute system(ATPS),a nonlinear finite element algorithm and a preconditioning finite volume method are employed ...In order to simulate and analyze the dynamic characteristics of the parachute from advanced tactical parachute system(ATPS),a nonlinear finite element algorithm and a preconditioning finite volume method are employed and developed to construct three dimensional parachute fluid-structure interaction(FSI)model.Parachute fabric material is represented by membrane-cable elements,and geometrical nonlinear algorithm is employed with wrinkling technique embedded to simulate the large deformations of parachute structure by applying the NewtonRaphson iteration method.On the other hand,the time-dependent flow surrounding parachute canopy is simulated using preconditioned lower-upper symmetric Gauss-Seidel(LU-SGS)method.The pseudo solid dynamic mesh algorithm is employed to update the flow-field mesh based on the complex and arbitrary motion of parachute canopy.Due to the large amount of computation during the FSI simulation,massage passing interface(MPI)parallel computation technique is used for all those three modules to improve the performance of the FSI code.The FSI method is tested to simulate one kind of ATPS parachutes to predict the parachute configuration and anticipate the parachute descent speeds.The comparison of results between the proposed method and those in literatures demonstrates the method to be a useful tool for parachute designers.展开更多
Biomechanical properties of cells play a very important role in regulating cells function. Experimental studies found that when Leukocytes move near the vessel wall, the phenomena such as rolling, jumping and adhesion...Biomechanical properties of cells play a very important role in regulating cells function. Experimental studies found that when Leukocytes move near the vessel wall, the phenomena such as rolling, jumping and adhesion will appear. Based on the non-linear fluid-structure interaction theory, leukocyte’s tiny jumping mechanism and rolling phenomenon were studied. The results were: 1) The choice of time step of leukocyte had a great influence on the movement of leukocyte. Instead of landing on the bottom of flow chamber, leukocyte jumped to a certain height and then moved periodically toward the bottom of the flow chamber again. Leukocyte had the biggest deformation when jumping;2) Adhesion and rolling along the bottom of the flow chamber appeared in the process of moving forward, the scrolling speed was greater than that of pure rolling. Leukocytes’ movement in blood vessels was closely related with body physiological and pathological characteristics. The study of dynamic movement of leukocyte provided theoretical basis for clinical medicine.展开更多
In this paper, accurate and efficient simulation of cell motion in a biological fluid flow is investigated. The membrane of a moving cell is represented by athin shell composed of incompressible neo-Hookean elastic ma...In this paper, accurate and efficient simulation of cell motion in a biological fluid flow is investigated. The membrane of a moving cell is represented by athin shell composed of incompressible neo-Hookean elastic materials and the liquidsaround the membrane are approximated as incompressible Newtonian flows with lowReynolds numbers. The biofluid mechanics is approximated by the Stokes flow equations. A low-order BEM model is developed for the two biological fluids coupled atthe membrane surface. The moving boundary problem in fluid mechanics can be effectively solved using the BEM with a GMRES solver. The FEM model based on a flatthin shell element is further developed to predict the membrane load due to the largedeformation of a moving cell. Computational efficiency is greatly improved due tothe one-dimensional reduction in the present BEM and FEM models. The BEM solverfor the biological fluids is coupled with the FEM solver for the cell membrane at themembrane surface. The position of the membrane surface nodes is advanced in time byusing the classical fourth-order Runge-Kutta method. Numerical instability is avoidedby using a relatively small time step. Further numerical instabilities in the FEM solveris alleviated by using various techniques. The present method is applied to the FSIproblems of cell motion in a cylindrical flow. Numerical examples can illustrate thedistinct accuracy, efficiency and robustness of the present method. Furthermore, theimportance of bending stiffness of a cell membrane for stable cell motion simulation isemphasized. It is suggested that the present approach be an appealing alternative forsimulating the fluid-structure interaction of moving cells.展开更多
Fluid-structure-particle interactions in three spatial dimensions happen in many environmental and engineering flows.This paper presents the parallel algorithms for the hybrid diffuse and sharp interface immersed boun...Fluid-structure-particle interactions in three spatial dimensions happen in many environmental and engineering flows.This paper presents the parallel algorithms for the hybrid diffuse and sharp interface immersed boundary(IB)method developed in our previous work.For the moving structure modeled using the sharp interface IB method,a recursive box method is developed for efficiently classifying the background grid nodes.For the particles modeled using the diffuse interface IB method,a‘master-slave’approach is adopted.For the particle-particle interaction(PPI)and particle-structure interaction(PSI),a fast algorithm for classifying the active and inactive Lagrangian points,which discretize the particle surface,is developed for the‘dry’contact approach.The results show that the proposed recursive box method can reduce the classifying time from 52seconds to 0.3 seconds.Acceptable parallel efficiency is obtained for cases with different particle concentrations.Furthermore,the lubrication model is utilized when a particle approaches a wall,enabling an accurate simulation of the rebounding phenomena in the benchmark particle-wall collision problem.At last,the capability of the proposed computational framework is demonstrated by simulating particle-laden turbulent channel flows with rough walls.展开更多
Debris flow can cause serious damage,and it is a part of the study of fluid-structure interaction(FSI).FSI analysis was established on the interaction between unsteady flow and the slit-trap dam's vibration,with a...Debris flow can cause serious damage,and it is a part of the study of fluid-structure interaction(FSI).FSI analysis was established on the interaction between unsteady flow and the slit-trap dam's vibration,with a coupling bench which can transfer fluid pressure and structure displacement.Debris flow can be seen as the Bingham body of incompressible.Based on ANSYS and CFX softwares,unidirectional and bidirectional coupling methods were used to study the transient interaction between debris flow and dam.The comparison between lateral fluid pressure states under different velocities and the equivalent stresses of the dam under different coupling conditions was made.The result shows that fluid-structure coupling becomes stronger with the increase of flow velocity.The maximum equivalent stress appears at the dam foundation,while the minimum equivalent stress appears at the dam abutment.With the increase of height,the fluid pressure decreases.The fluid pressure based on unidirectional FSI analysis is larger than that based on bidirectional FSI analysis and the maximum appears on the joint of the dam foundation and channel.The maximum equivalent stress of the dam based on the former is less than that based on the latter.展开更多
Submarine pipelines are critical infrastructures for offshore energy transport and communications. Understanding their structural response to near-field explosions is crucial for enhancing their blast resistance and o...Submarine pipelines are critical infrastructures for offshore energy transport and communications. Understanding their structural response to near-field explosions is crucial for enhancing their blast resistance and operational safety. This study presents a computational study on the interaction between explosion-induced bubbles and a seabed-mounted pipeline. A recently developed computational framework is employed, which couples a compressible fluid solver with a finite element structural solver via a partitioned procedure. An embedded boundary method and a level-set method are employed to handle the fluid-structure and gas-liquid interfaces. Using this framework, we analyze the flow field evolution, bubble dynamics, and transient pipe deformation. Two distinct response modes are identified: periodic oscillation under low-pressure loading and downward collapse triggered by high-pressure loading and bubble jet impact. Specifically, under high-pressure conditions, the pipe initially deforms inward, generating a localized high-pressure zone within the concave region. During structural rebound, the trapped fluid is expelled upward, giving rise to a bubble jet. Further parametric studies on the pipe's internal pressure, wall thickness, and support angle reveal several key insights. A higher internal pressure delays structural collapse, and a greater pipe thickness results in more uniform implosion morphologies. The support angle strongly influences the collapse dynamics, with the shortest collapse time occurring at 60 °. These findings offer new insights for the protective design of submarine pipelines.展开更多
The flow control at low Reynolds numbers is one of the most promising technologies in the field of aerodynamics,and it is also an important source of the innovation for novel aircraft.In this study,a new way of nonlin...The flow control at low Reynolds numbers is one of the most promising technologies in the field of aerodynamics,and it is also an important source of the innovation for novel aircraft.In this study,a new way of nonlinear flow control by interaction between two flexible flaps is proposed,and their flow control mechanism is studied employing the self-constructed immersed boundary-lattice Boltzmann-finite element method(IB-LB-FEM).The effects of the difference in material properties and flap length between the two flexible flaps on the nonlinear flow control of the airfoil are discussed.It is suggested that the relationship between the deformation of the two flexible flaps and the evolution of the vortex under the fluid-structure interaction(FSI).It is shown that the upstream flexible flap plays a key role in the flow control of the two flexible flaps.The FSI effect of the upstream flexible flap will change the unsteady flow behind it and affect the deformation of the downstream flexible flap.Two flexible flaps with different material properties and different lengths will change their own FSI characteristics by the induced vortex,effectively suppressing the flow separation on the airfoil’s upper surface.The interaction of two flexible flaps plays an extremely important role in improving the autonomy and adjustability of flow control.The numerical results will provide a theoretical basis and technical guidance for the development and application of a new flap passive control technology.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
The oceanic mixed layer in the Southern Ocean is characterized by numerous fronts due to the stirring of freshwater influxes arising from ice melting.The interaction of these fronts with winds modulates the evolution ...The oceanic mixed layer in the Southern Ocean is characterized by numerous fronts due to the stirring of freshwater influxes arising from ice melting.The interaction of these fronts with winds modulates the evolution of the mixed layer and affects atmosphere−ocean energy exchanges.However,the underlying mechanism behind the wind-front interaction remains obscure due to a lack of three-dimensional observations of the ocean,particularly in terms of velocities.To address this issue,this study investigates the dynamics of fronts within the mixed layer during a storm by employing a subset of the global submesoscale-permitting simulation,Northeast Weddell Sea Pre-SWOT Level-4 Hourly MITgcm LLC4320 Native Grid 2km Oceanographic Dataset(ROAM_MIZ).We first compare the ROAM_MIZ data to glider data to assess the performance of the model simulation and find that the ROAM_MIZ can,to a large degree,capture sub-mesoscale features within a mixed layer.Subsequent analyses based on a subset of ROAM_MIZ show that lateral density gradients within the mixed layer rapidly decrease during high winds associated with the storm.Down-front winds accelerate this process as the Ekman buoyancy transport responsible for enhancing the instability of the fronts is primarily dominated by horizontal baroclinic components.After the storm,the fronts strengthen again in the presence of weaker winds due to the frontogenesis by the larger-scale strain.Moreover,the non-geostrophic turbulence induces a modification of the relative vorticity,affecting the instability within the mixed layer.These findings offer valuable guidance for the deployment of observational instruments and subsequent analysis,as well as deepen the understanding of air−sea interactions in the Southern Ocean.展开更多
基金supported by the Chongqing Natural Science Foundation of Chongqing,China(No.CSTB2022NSCQ-MSX0333)the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-K202401205)+1 种基金Chongqing Three Gorges University Graduate Research and Innovation Project Funding(No.YJSKY24045)Chongqing Engineering Research Center of Disaster Prevention&Control for Banks and Structures in Three Gorges Reservoir Area(No.SXAPGC24YB14,No.SXAPGC24YB03,No.SXAPGC24YB12)。
文摘Oil shale is characterized by a dense structure,low proportion of pores and fissures,and low permeability.Pore-fracture systems serve as crucial channels for shale oil migration,directly influencing the production efficiency of shale oil resources.Effectively stimulating oil shale reservoirs remains a challenging and active research topic.This investigation employed shale specimens obtained from the Longmaxi Formation.Scanning electron microscopy,fluid injection experiments,and fluid-structure interaction simulations were used to comprehensively analyze structural changes and fluid flow behavior under high temperatures from microscopic to macroscopic scales.Experimental results indicate that the temperature has little effect on the structure and permeability of shale before 300℃.However,there are two threshold temperatures within the range of 300 to 600℃that have significant effects on the structure and permeability of oil shale.The first threshold temperature is between 300 and 400℃,which causes the oil shale porosity,pore-fracture ratio,and permeability begin to increase.This is manifested by the decrease in micropores and mesopores,the increase in macropores,and the formation of a large number of isolated pores and fissures within the shale.The permeability increases but not significantly.The second threshold temperature is between 500 and 600℃,which increases the permeability of oil shale significantly.During this stage,micropores and mesopores are further reduced,and macropores are significantly enlarged.A large number of connected and penetrated pores and fissures are formed.More numerous and thicker streamlines appear inside the oil shale.The experimental results demonstrate that high temperatures significantly alter the microstructure and permeability of oil shale.At the same time,the experimental results can provide a reference for the research of in-situ heating techniques in oil shale reservoir transformation.
基金Project supported by the National Natural Science Foundation of China(No.10832007)the Shanghai Leading Academic Discipline Project(No.B206)
文摘The closely coupled approach combined with the finite volume method （FVM） solver and the finite element method （FEM） solver is used to investigate the fluid-structure interaction （FSI） of a three-dimensional cantilevered hydrofoil in the water tunnel. The FVM solver and the coupled approach are verified and validated by compar- ing the numerical predictions with the experimental measurements, and good agreement is obtained concerning both the lift on the foil and the tip displacement. In the noncav- itating flow, the result indicates that the growth of the initial incidence angle and the Reynolds number improves the deformation of the foil, and the lift on the foil is increased by the twist deformation. The normalized twist angle and displacement along the span of the hydrofoil for different incidence angles and Reynolds numbers are almost uniform. For the cavitation flow, it is shown that the small amplitude vibration of the foil has limited influence on the developing process of the partial cavity, and the quasi two-dimensional cavity shedding does not change the deformation mode of the hydrofoil. However, the frequency spectrum of the lift on the foil contains the frequency which is associated with the first bend frequency of the hydrofoil.
基金This work study is financially supported by the National Natural Science Foundation of China(Nos.31570952,10802053,81471702)the Natural Science Foundation of Beijing(No.3122010)。
文摘Elevated intraocular pressure appears to have a broader impact on increased resistance to aqueous humor outflow through the conventional aqueous outflow system(AOS).However,there is still no consensus about exact location of the increased outflow resistance of aqueous humor,and the mechanism is not perfect.In addition,it is difficult to accurately obtain hydrodynamic parameters of aqueous humor within the trabecular meshwork outflow pathways based on the current technology.In this paper,a two-way fluid-structure interaction simulation was performed to study the pressure difference and velocity in the superficial trabecular meshwork,juxtacanalicular meshwork(JCM)and Schlemm’s canal in response to JCM permeability changes.We obtained the JCM permeability of normal intraocular pressure varied between 1×10?15 m2 and 10×10?15 m2 while permeability of the JCM ranged from 2×10?16 m2 and 3×10?16 m2 under conditions of high intraocular pressure.The study indicated that the fluid dynamics parameters in trabecular meshwork and Schlemm’s canal are most significantly affected by the changes of JCM permeability.Moreover,the study demonstrates that the finite element modeling of AOS provides a practical means for studying the outflow dynamics and the biomechanical environment of the AOS.
基金supported by the National Natural Science Foundation of China(Nos.52192633,11872293)the Natural Science Foundation of Shaanxi Province,China(No.2022JC-03)。
文摘The multi-body flexible morphing airfoil can improve the aerodynamic characteristics based on different flight missions continuously.Recently researches have focused on the unsteady aerodynamic characteristics of flexible wings under passive actuation.However,the unsteady aerodynamic characteristics with the fluid-structure interaction effects in the multi-body active actuation process of morphing airfoil deserve further investigation.In this paper,a fluid-structure coupled simulation method for multi-body flexible morphing airfoil with active actuation subsystem was investigated,and the aerodynamic characteristics during deformation were compared with different skin flexibility,flow field environment,actuation mode and actuation time.The numerical results show that for the steady aerodynamic,the skin flexibility can improve the stability efficiency.In the unsteady process,the change trend of the transient lift coefficient and pitching moment are consistent with those of the active drive characteristics,while the instantaneous lift-drag ratio coefficient is greatly affected by the driving mode and can be improved by increasing the driving duration.
基金The article received China National Natural Science Found(41601574).
文摘Based on the theories of the gas seepage in coal seams and the deformation of the coal-rock medium,the gas seepage field in coal-rock mass is coupled with the deformation field of the coal-rock mass to establish a fluidstructure interaction model for the interaction between coal gas and coal-rock masses.The outburst process in coal-rock masses under the joint action of gas pressure and crustal stress is simulated using the material point method.The simulation results show the changes in gas pressure,velocity distribution,maximum principal stress distribution,and damage distribution during the process of the coal and gas outburst,as well as themovement and accumulation of coal-rock masses after the occurrence of the outburst.It was found that the gas pressure gradient was greatest at theworking face after the occurrence of the outburst,the gas pressures and pressure gradients at each location within the coal seamgradually decreased with time,and the damage distribution was essentially the same as the minimum principal stress distribution.The simulation further revealed that the outburst first occurred in themiddle of the tunnel excavation face and that the speed at which particles of coal mass were ejected was highest at the center and decreased toward the upper and lower sides.The study provides a scientific basis for enhancing our understanding of the mechanism behind coal and gas outbursts,as well as their prevention and control.
基金supported by the National Key R&D Program of China under Grant No.2020YFB1709402the NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization(Grant No.U1909210)+1 种基金the National Natural Science Foundation ofChina(Grant Nos.61772163,U22A2033,62072148)ZhejiangLabTianshuOpen Source AI Platform,the Zhejiang Provincial Science and Technology Program in China under Grant 2021C01108.
文摘In order to improve the efficiency of heart valve simulation,we proposed a fast isogeometric simulation approach for time-dependent heart valve simulation algorithm with the idea of Geometric-Independent Field approximation(GIFT for short).For the solution of the blood flow field problem in a heart valve,the fluid background mesh is first simplified,then a Bézier tetrahedral mesh is generated based on the simplified mesh to maintain geometric precision,and finally,the fluid velocity field and pressure are solved.In addition,the GIFT idea is used to represent the geometry of computational domain geometry and approximate the physical field solution with different basis function spaces to obtain the numerical solution with the same precision as before simplification.In the structural mechanics simulation of valve leaflets,NURBS surfaces are used to represent the geometric model.To avoid degeneration on geometric boundary,a single leaflet geometric patch is subdivided into four patches.The immersion geometry strategy is adopted in solving the deformation problem of cardiac valve leaflets to achieve high simulation precision,and the dynamic augmented Lagrangian algorithm is used to couple fluid-structure control equations.For the time discretization,the generalizedαmethod is used to control high-frequency dissipation.Numerical examples and comparisons with previous methods are also presented.The proposed algorithm can reduce the computing costs by about 54.3%,which proves the effectiveness of the proposed method.
基金The project supported by the National Natural Science Foundation of China(10672036,10472025 and 10421002)the Natural Science Foundation of Liaoning Province(20032109)
文摘In this paper, the authors present airflow field characteristics of human upper airway and soft palate movement attitude during breathing. On the basis of the data taken from the spiral computerized tomography images of a healthy person and a patient with Obstructive Sleep Apnea-Hypopnea Syndrome （OSAHS）, three-dimensional models of upper airway cavity and soft palate are reconstructed by the method of surface rendering. Numerical simulation is performed for airflow in the upper airway and displacement of soft palate by fluid-structure interaction analysis. The reconstructed threedimensional models precisely preserve the original configuration of upper airways and soft palate. The results of the pressure and velocity distributions in the airflow field are quantitatively determined, and the displacement of soft palate is presented. Pressure gradients of airway are lower for the healthy person and the airflow distribution is quite uniform in the case of free breathing. However, the OSAHS patient remarkably escalates both the pressure and velocity in the upper airway, and causes higher displacement of the soft palate. The present study is useful in revealing pathogenesis and quantitative mutual relationship between configuration and function of the upper airway as well as in diagnosingdiseases related to anatomical structure and function of the upper airway.
基金This project is supported by National 863 Hi-Tech Project Foundation (No. 2002AA411030).
文摘An effective computational method is developed for dynamic analysis offluid-structure interaction problems involving large-amplitude sloshing of the fluid andlarge-displacement motion of the structure. The structure is modeled as a rigid container supportedby a system consisting of springs and dashpots. The motion of the fluid is decomposed into twoparts: the large-displacement motion with the container and the large-amplitude sloshing relative tothe container. The former is conveniently dealt with by defining a container-fixed noninertiallocal frame, while the latter is easily handled by adopting an ALE kinematical description. Thisleads to an easy and accurate treatment of both the fluid-structure interface and the fluid freesurface without producing excessive distortion of the computational mesh. The coupling between thefluid and the structure is accomplished through the coupling matrices that can be easilyestablished. Two numerical examples, including a TLD-structure system and a simplified liquid-loadedvehicle system, are presented to demonstrate the effectiveness and reliability of the proposedmethod. The present work can also be applied to simulate fluid-structure problems incorporatingmultibody systems and several fluid domains.
基金Project supported by the Program for New Century Excellent Talents in University (No. NCET-10-0054)the Fok Ying-Tong Education Foundation,China (No. 121073)+1 种基金the National Natural Science Foundation of China (No. 10976008)the State Key Program of National Natural Science of China (No. 50939002)
文摘In the underwater-shock environment, cavitation occurs near the structural surface. The dynamic response of fluid-structure interactions is influenced seriously by the cavitation effects. It is also the difficulty in the field of underwater explosion. With the traditional boundary element method and the finite element method （FEM）, it is difficult to solve the nonlinear problem with cavitation effects subjected to the underwater explosion. To solve this problem, under the consideration of the cavitation effects and fluid compressibility, with fluid viscidity being neglected, a 3D numerical model of transient nonlinear fluid-structure interaction subjected to the underwater explosion is built. The fluid spectral element method （SEM） and the FEM are adopted to solve this model. After comparison with the FEM, it is shown that the SEM is more precise than the FEM, and the SEM results are in good coincidence with benchmark results and experiment results. Based on this, combined with ABAQUS, the transient fluid-structure interaction mechanism of the 3D submerged spherical shell and ship stiffened plates subjected to the underwater explosion is discussed, and the cavitation region and its influence on the structural dynamic responses are presented. The paper aims at providing references for relevant research on transient fluid-structure interaction of ship structures subjected to the underwater explosion.
文摘This article introduces a numerical scheme on the basis of semi-implicit method for pressure-linked equations （SIMPLE） algorithm to simulate incompressible unsteady flows with fluid-structure interaction. The Navier-Stokes equation is discretized spatially with collocated finite volume method and Eulerian implicit method in time domain. The hybrid method that combines immersed boundary method （IBM） and volume of fluid （VOF） method is used to deal with rigid body motion in fluid domain. The details of movement of immersed boundary （IB） and calculation of VOF are also described. This method can be easily applied to any existing finite-volume-based computational fluid dynamics （CFD） solver without complex operation, with which fluid flow interaction of arbitrarily complex geometry can be realized on a fixed mesh. The method is verified by low Reynolds number flows passing both stationary and oscillating cylinders. The drag and lift coefficients acquired by the study well accord with other published results, which indicate the reasonability of the proposed method.
文摘Fluid-structure interaction （FSI） problems in microchannels play a prominent role in many engineering applications. The present study is an effort toward the simulation of flow in microchannel considering FSI. The bottom boundary of the microchannel is simulated by size-dependent beam elements for the finite element method （FEM） based on a modified cou- ple stress theory. The lattice Boltzmann method （LBM） using the D2Q13 LB model is coupled to the FEM in order to solve the fluid part of the FSI problem. Because of the fact that the LBM generally needs only nearest neighbor information, the algorithm is an ideal candidate for parallel computing. The simulations are carried out on graphics processing units （GPUs） using computed unified device architecture （CUDA）. In the present study, the governing equations are non-dimensionalized and the set of dimensionless groups is exhibited to show their effects on micro-beam displacement. The numerical results show that the displacements of the micro-beam predicted by the size-dependent beam element are smaller than those by the classical beam element.
文摘In order to simulate and analyze the dynamic characteristics of the parachute from advanced tactical parachute system(ATPS),a nonlinear finite element algorithm and a preconditioning finite volume method are employed and developed to construct three dimensional parachute fluid-structure interaction(FSI)model.Parachute fabric material is represented by membrane-cable elements,and geometrical nonlinear algorithm is employed with wrinkling technique embedded to simulate the large deformations of parachute structure by applying the NewtonRaphson iteration method.On the other hand,the time-dependent flow surrounding parachute canopy is simulated using preconditioned lower-upper symmetric Gauss-Seidel(LU-SGS)method.The pseudo solid dynamic mesh algorithm is employed to update the flow-field mesh based on the complex and arbitrary motion of parachute canopy.Due to the large amount of computation during the FSI simulation,massage passing interface(MPI)parallel computation technique is used for all those three modules to improve the performance of the FSI code.The FSI method is tested to simulate one kind of ATPS parachutes to predict the parachute configuration and anticipate the parachute descent speeds.The comparison of results between the proposed method and those in literatures demonstrates the method to be a useful tool for parachute designers.
文摘Biomechanical properties of cells play a very important role in regulating cells function. Experimental studies found that when Leukocytes move near the vessel wall, the phenomena such as rolling, jumping and adhesion will appear. Based on the non-linear fluid-structure interaction theory, leukocyte’s tiny jumping mechanism and rolling phenomenon were studied. The results were: 1) The choice of time step of leukocyte had a great influence on the movement of leukocyte. Instead of landing on the bottom of flow chamber, leukocyte jumped to a certain height and then moved periodically toward the bottom of the flow chamber again. Leukocyte had the biggest deformation when jumping;2) Adhesion and rolling along the bottom of the flow chamber appeared in the process of moving forward, the scrolling speed was greater than that of pure rolling. Leukocytes’ movement in blood vessels was closely related with body physiological and pathological characteristics. The study of dynamic movement of leukocyte provided theoretical basis for clinical medicine.
文摘In this paper, accurate and efficient simulation of cell motion in a biological fluid flow is investigated. The membrane of a moving cell is represented by athin shell composed of incompressible neo-Hookean elastic materials and the liquidsaround the membrane are approximated as incompressible Newtonian flows with lowReynolds numbers. The biofluid mechanics is approximated by the Stokes flow equations. A low-order BEM model is developed for the two biological fluids coupled atthe membrane surface. The moving boundary problem in fluid mechanics can be effectively solved using the BEM with a GMRES solver. The FEM model based on a flatthin shell element is further developed to predict the membrane load due to the largedeformation of a moving cell. Computational efficiency is greatly improved due tothe one-dimensional reduction in the present BEM and FEM models. The BEM solverfor the biological fluids is coupled with the FEM solver for the cell membrane at themembrane surface. The position of the membrane surface nodes is advanced in time byusing the classical fourth-order Runge-Kutta method. Numerical instability is avoidedby using a relatively small time step. Further numerical instabilities in the FEM solveris alleviated by using various techniques. The present method is applied to the FSIproblems of cell motion in a cylindrical flow. Numerical examples can illustrate thedistinct accuracy, efficiency and robustness of the present method. Furthermore, theimportance of bending stiffness of a cell membrane for stable cell motion simulation isemphasized. It is suggested that the present approach be an appealing alternative forsimulating the fluid-structure interaction of moving cells.
基金Project supported by the National Natural Science Foundation of China(Nos.12202456 and12172360)the Basic Science Center Program for“Multiscale Problems in Nonlinear Mechanics”of the National Natural Science Foundation of China(No.11988102)the China Postdoctoral Science Foundation(No.2021M693241)。
文摘Fluid-structure-particle interactions in three spatial dimensions happen in many environmental and engineering flows.This paper presents the parallel algorithms for the hybrid diffuse and sharp interface immersed boundary(IB)method developed in our previous work.For the moving structure modeled using the sharp interface IB method,a recursive box method is developed for efficiently classifying the background grid nodes.For the particles modeled using the diffuse interface IB method,a‘master-slave’approach is adopted.For the particle-particle interaction(PPI)and particle-structure interaction(PSI),a fast algorithm for classifying the active and inactive Lagrangian points,which discretize the particle surface,is developed for the‘dry’contact approach.The results show that the proposed recursive box method can reduce the classifying time from 52seconds to 0.3 seconds.Acceptable parallel efficiency is obtained for cases with different particle concentrations.Furthermore,the lubrication model is utilized when a particle approaches a wall,enabling an accurate simulation of the rebounding phenomena in the benchmark particle-wall collision problem.At last,the capability of the proposed computational framework is demonstrated by simulating particle-laden turbulent channel flows with rough walls.
基金Science and Technology Support Program,China(No.2014BAL05B01)Project of Institute of Mountain Hazards and Environment of Chinese Academy of Sciences,China(No.KZZD-EW-Q5-Q1)
文摘Debris flow can cause serious damage,and it is a part of the study of fluid-structure interaction(FSI).FSI analysis was established on the interaction between unsteady flow and the slit-trap dam's vibration,with a coupling bench which can transfer fluid pressure and structure displacement.Debris flow can be seen as the Bingham body of incompressible.Based on ANSYS and CFX softwares,unidirectional and bidirectional coupling methods were used to study the transient interaction between debris flow and dam.The comparison between lateral fluid pressure states under different velocities and the equivalent stresses of the dam under different coupling conditions was made.The result shows that fluid-structure coupling becomes stronger with the increase of flow velocity.The maximum equivalent stress appears at the dam foundation,while the minimum equivalent stress appears at the dam abutment.With the increase of height,the fluid pressure decreases.The fluid pressure based on unidirectional FSI analysis is larger than that based on bidirectional FSI analysis and the maximum appears on the joint of the dam foundation and channel.The maximum equivalent stress of the dam based on the former is less than that based on the latter.
基金supported by the National Key R&D Program of China(Grant No.2024YFC3013200)the Shenzhen Peacock Plan(Grant No.QD2023006C).
文摘Submarine pipelines are critical infrastructures for offshore energy transport and communications. Understanding their structural response to near-field explosions is crucial for enhancing their blast resistance and operational safety. This study presents a computational study on the interaction between explosion-induced bubbles and a seabed-mounted pipeline. A recently developed computational framework is employed, which couples a compressible fluid solver with a finite element structural solver via a partitioned procedure. An embedded boundary method and a level-set method are employed to handle the fluid-structure and gas-liquid interfaces. Using this framework, we analyze the flow field evolution, bubble dynamics, and transient pipe deformation. Two distinct response modes are identified: periodic oscillation under low-pressure loading and downward collapse triggered by high-pressure loading and bubble jet impact. Specifically, under high-pressure conditions, the pipe initially deforms inward, generating a localized high-pressure zone within the concave region. During structural rebound, the trapped fluid is expelled upward, giving rise to a bubble jet. Further parametric studies on the pipe's internal pressure, wall thickness, and support angle reveal several key insights. A higher internal pressure delays structural collapse, and a greater pipe thickness results in more uniform implosion morphologies. The support angle strongly influences the collapse dynamics, with the shortest collapse time occurring at 60 °. These findings offer new insights for the protective design of submarine pipelines.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.92371201,52192633,11872293,and 92152301)the Natural Science Basic Research Program of Shaanxi(Grant Nos.2024JC-YBQN-0008,and 2022JC-03)+1 种基金Shaanxi Key Research and Development Program(Grant No.2022ZDLGY02-07)the Joint Natural Science Foundation of China with Guangdong Province for TianHe-II Supercomputer Resources,and the Research Start-up Foundation of Xi’an University of Science and Technology for the High-Level Talent.
文摘The flow control at low Reynolds numbers is one of the most promising technologies in the field of aerodynamics,and it is also an important source of the innovation for novel aircraft.In this study,a new way of nonlinear flow control by interaction between two flexible flaps is proposed,and their flow control mechanism is studied employing the self-constructed immersed boundary-lattice Boltzmann-finite element method(IB-LB-FEM).The effects of the difference in material properties and flap length between the two flexible flaps on the nonlinear flow control of the airfoil are discussed.It is suggested that the relationship between the deformation of the two flexible flaps and the evolution of the vortex under the fluid-structure interaction(FSI).It is shown that the upstream flexible flap plays a key role in the flow control of the two flexible flaps.The FSI effect of the upstream flexible flap will change the unsteady flow behind it and affect the deformation of the downstream flexible flap.Two flexible flaps with different material properties and different lengths will change their own FSI characteristics by the induced vortex,effectively suppressing the flow separation on the airfoil’s upper surface.The interaction of two flexible flaps plays an extremely important role in improving the autonomy and adjustability of flow control.The numerical results will provide a theoretical basis and technical guidance for the development and application of a new flap passive control technology.
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supported by the National Natural Science Foundation of China (Grant Nos. 42406241,42325604,42227901)the Ministry of Science and Technology of China (No. 2021YFC2803304)+2 种基金the Program of Shanghai Academic/Technology Research Leader (22XD1403600)supported by the Swedish Research Council (Nos. 2020–03190 and 2024-04209)the Swedish Research Council for the Environment, Agricultural Sciences and Spatial Planning (No. 202400375)
文摘The oceanic mixed layer in the Southern Ocean is characterized by numerous fronts due to the stirring of freshwater influxes arising from ice melting.The interaction of these fronts with winds modulates the evolution of the mixed layer and affects atmosphere−ocean energy exchanges.However,the underlying mechanism behind the wind-front interaction remains obscure due to a lack of three-dimensional observations of the ocean,particularly in terms of velocities.To address this issue,this study investigates the dynamics of fronts within the mixed layer during a storm by employing a subset of the global submesoscale-permitting simulation,Northeast Weddell Sea Pre-SWOT Level-4 Hourly MITgcm LLC4320 Native Grid 2km Oceanographic Dataset(ROAM_MIZ).We first compare the ROAM_MIZ data to glider data to assess the performance of the model simulation and find that the ROAM_MIZ can,to a large degree,capture sub-mesoscale features within a mixed layer.Subsequent analyses based on a subset of ROAM_MIZ show that lateral density gradients within the mixed layer rapidly decrease during high winds associated with the storm.Down-front winds accelerate this process as the Ekman buoyancy transport responsible for enhancing the instability of the fronts is primarily dominated by horizontal baroclinic components.After the storm,the fronts strengthen again in the presence of weaker winds due to the frontogenesis by the larger-scale strain.Moreover,the non-geostrophic turbulence induces a modification of the relative vorticity,affecting the instability within the mixed layer.These findings offer valuable guidance for the deployment of observational instruments and subsequent analysis,as well as deepen the understanding of air−sea interactions in the Southern Ocean.
