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Specific heat ratio effects of compressible Rayleigh—Taylor instability studied by discrete boltzmann method

Frontiers of physics 2021年第5期16卷 199-210页

作者：陈璐赖惠林林传栋李德梅 College of Mathematics and Statistics FJKLMAACenter for Applied Mathematics of Fujian Province(FJNU)Fujian Normal UniversityFuzhou350117China Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai519082China

Rayleigh-Taylor(RT)instability widely exists in nature and engineering *** to better understand the physical mechanism of RT instability is of great theoretical significance and practical *** present,abundant results of RT instability have been obtained by traditional macroscopic ***,research on the thermodynamic non-equilibrium(TNE)effects in the process of system evolution is relatively *** this paper,the discrete boltzmann method based on non-equilibrium statistical physics is utilized to study the effects of the specific heat ratio on compressible RT *** evolution process of the compressible RT system with different specific heat ratios can be analyzed by the temperature gradient and the proportion of the non-equilibrium ***,as a result of the competition between the macroscopic magnitude gradient and the non-equilibrium region,the average TNE intensity first increases and then reduces,and it increases with the specific heat ratio decreasing;the specific heat ratio has the same effect on the global strength of the viscous stress ***,the moment when the total temperature gradient in y direction deviates from the fixed value can be regarded as a physical criterion for judging the formation of the vortex ***,under the competition between the temperature gradients and the contact area of the two fluids,the average intensity of the non-equilibrium quantity related to the heat flux shows diversity,and the influence of the specific heat ratio is also quite remarkable.

关键词： discrete boltzmann method Rayleigh-Taylor instability non-equilibrium effects specific heat ratio effects compressible fluid

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Advances in the kinetics of heat and mass transfer in near-continuous complex flows

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Frontiers of physics 2024年第4期19卷 187-234页

作者：许爱国张德佳甘延标 National Key Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsP.O.Box 8009-26Beijing 100088China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China State Key Laboratory for GeoMechanics and Deep Underground Engineering China University of Mining and TechnologyBeijing 100083China National Key Laboratory of Shock Wave and Detonation Physics Mianyang 621999China Hebei Key Laboratory of Trans-Media Aerial Underwater Vehicle School of Liberal Arts and SciencesNorth China Institute of Aerospace EngineeringLangfang 065000China

The study of macro continuous flow has a long ***,the exploration of heat and mass transfer in small systems with a particle number of several hundred or less has gained significant interest in the fields of statistical physics and nonlinear ***,due to absence of suitable methods,the understanding of mesoscale behavior situated between the aforementioned two scenarios,which challenges the physical function of traditional continuous fluid theory and exceeds the simulation capability of microscopic molecular dynamics method,remains considerably *** greatly restricts the evaluation of effects of mesoscale behavior and impedes the development of corresponding regulation *** access the mesoscale behaviors,there are two ways:from large to small and from small to *** the necessity to interface with the prevailing macroscopic continuous modeling currently used in the mechanical engineering community,our study of mesoscale behavior begins from the side closer to the macroscopic continuum,that is from large to *** on some fundamental challenges encountered in modeling and analysis of near-continuous flows,we review the research progress of discrete boltzmann method(DBM).The ideas and schemes of DBM in coarse-grained modeling and complex physical field analysis are *** relationships,particularly the differences,between DBM and traditional fluid modeling as well as other kinetic methods are *** verification and validation of the method,some applied researches including the development of various physical functions associated with discrete and non-equilibrium effects are *** directions of DBM related studies are indicated.

关键词： near-continuous flow non-equilibrium kinetics discrete boltzmann method complex physical field analysis

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discrete boltzmann model with split collision for nonequilibrium reactive flows

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Communications in Theoretical Physics 2024年第08期76卷 166-188页

作者： Chuandong Lin Kai H Luo Huilin Lai Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen University Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power Engineering Tsinghua University Department of Mechanical Engineering National University of Singapore Department of Mechanical Engineering University College London School of Mathematics and Statistics Key Laboratory of Analytical Mathematics and Applications (Ministry of Education) Fujian Key Laboratory of Analytical Mathematics and Applications (FJKLAMA) Center for Applied Mathematics of Fujian Province (FJNU) Fujian Normal University

A multi-relaxation-time discrete boltzmann model(DBM) with split collision is proposed for both subsonic and supersonic compressible reacting flows, where chemical reactions take place among various components. The physical model is based on a unified set of discrete boltzmann equations that describes the evolution of each chemical species with adjustable acceleration, specific heat ratio, and Prandtl number. On the right-hand side of discrete boltzmann equations, the collision,force, and reaction terms denote the change rates of distribution functions due to self-and crosscollisions, external forces, and chemical reactions, respectively. The source terms can be calculated in three ways, among which the matrix inversion method possesses the highest physical accuracy and computational efficiency. Through Chapman–Enskog analysis, it is proved that the DBM is consistent with the reactive Navier–Stokes equations, Fick's law and the Stefan–Maxwell diffusion equation in the hydrodynamic limit. Compared with the one-step-relaxation model, the split collision model offers a detailed and precise description of hydrodynamic, thermodynamic, and chemical nonequilibrium effects. Finally, the model is validated by six benchmarks, including multicomponent diffusion, mixture in the force field, Kelvin–Helmholtz instability, flame at constant pressure, opposing chemical reaction, and steady detonation.

关键词： detonation discrete boltzmann method nonequilibrium effect reactive flow

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Effects of the initial perturbations on the Rayleigh–Taylor–Kelvin–Helmholtz instability system

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Frontiers of physics 2022年第3期17卷 77-89页

作者：陈峰许爱国张玉东甘延标刘冰冰王爽 School of Aeronautics Shan Dong Jiaotong UniversityJinan 250357China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsP.O.Box 8009-26Beijing 100088China HEDPS Center for Applied Physics and Technologyand College of EngineeringPeking UniversityBeijing 100871China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China School of Mechanics and Safety Engineering Zhengzhou UniversityZhengzhou 450001China Hebei Key Laboratory of Trans-Media Aerial Underwater Vehicle North China Institute of Aerospace EngineeringLangfang 065000China Naval Architecture and Port Engineering College Shan Dong Jiaotong UniversityWeihai 264200China School of Science Shandong Jianzhu UniversityJinan 250101China

The effects of initial perturbations on the Rayleigh–Taylor instability (RTI), Kelvin–Helmholtz instability (KHI), and the coupled Rayleigh–Taylor–Kelvin–Helmholtz instability (RTKHI) systems are investigated using a multiple-relaxation-time discrete boltzmann model. Six different perturbation interfaces are designed to study the effects of the initial perturbations on the instability systems. It is found that the initial perturbation has a significant influence on the evolution of RTI. The sharper the interface, the faster the growth of bubble or spike. While the influence of initial interface shape on KHI evolution can be ignored. Based on the mean heat flux strength D3,1, the effects of initial interfaces on the coupled RTKHI are examined in detail. The research is focused on two aspects: (i) the main mechanism in the early stage of the RTKHI, (ii) the transition point from KHI-like to RTI-like for the case where the KHI dominates at earlier time and the RTI dominates at later time. It is found that the early main mechanism is related to the shape of the initial interface, which is represented by both the bilateral contact angle θ_(1) and the middle contact angle θ_(2). The increase of θ_(1) and the decrease of θ_(2) have opposite effects on the critical velocity. When θ_(2) remains roughly unchanged at 90 degrees, if θ_(1) is greater than 90 degrees (such as the parabolic interface), the critical shear velocity increases with the increase of θ_(1), and the ellipse perturbation is its limiting case;If θ_(1) is less than 90 degrees (such as the inverted parabolic and the inverted ellipse disturbances), the critical shear velocities are basically the same, which is less than that of the sinusoidal and sawtooth disturbances. The influence of inverted parabolic and inverted ellipse perturbations on the transition point of the RTKHI system is greater than that of other interfaces: (i) For the same amplitude, the smaller the contact angle θ_(1), the later the transitio

关键词： discrete boltzmann method hydrodynamic instability non-equilibrium characteristic initial perturbation

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Nonequilibrium effects of reactive fiow based on gas kinetic theory

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Communications in Theoretical Physics 2022年第3期74卷 104-111页

作者： Xianli Su Chuandong Lin Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

How to accurately probe chemically reactive fiows with essential thermodynamic nonequilibrium effects is an open *** the Chapman–Enskog analysis,the local nonequilibrium particle velocity distribution function is derived from the gas kinetic *** is demonstrated theoretically and numerically that the distribution function depends on the physical quantities and derivatives,and is independent of the chemical reactions directly as the chemical time scale is longer than the molecular relaxation *** on the simulation results of the discrete boltzmann model,the departure between equilibrium and nonequilibrium distribution functions is obtained and analyzed around the detonation *** addition,it has been verified for the first time that the kinetic moments calculated by summations of the discrete distribution functions are close to those calculated by integrals of their original forms.

关键词： discrete boltzmann method reactive fiow detonation nonequilibrium effect

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Influence of the tangential velocity on the compressible Kelvin–Helmholtz instability with nonequilibrium effects

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Frontiers of physics 2022年第6期17卷 125-141页

作者： Yaofeng Li Huilin Lai Chuandong Lin Demei Li College of Mathematics and Statistics FJKLMAACenter for Applied Mathematics of Fujian Province(FJNU)Fujian Normal UniversityFuzhou 350117China Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

Kelvin–Helmholtz(KH)instability is a fundamental fluid instability that widely exists in nature and *** better understand the dynamic process of the KH instability,the influence of the tangential velocity on the compressible KH instability is investigated by using the discrete boltzmann method based on the nonequilibrium statistical *** hydrodynamic and thermodynamic nonequilibrium(TNE)effects are probed and *** is found that,on the whole,the global density gradients,the TNE strength and area firstly increase and decrease *** the global density gradient and heat flux intensity in the vertical direction are almost constant in the initial stage before a vortex ***,with the increase of the tangential velocity,the KH instability evolves faster,hence the global density gradients,the TNE strength and area increase in the initial stage and achieve their peak earlier,and their maxima are higher for a larger tangential ***,there are several competitive mechanisms in the evolution of the KH instability.(i)The physical gradients increase and the TNE effects are strengthened as the interface is *** local physical gradients decrease and the local TNE intensity is weakened on account of the dissipation and/or diffusion.(ii)The global heat flux intensity is promoted when the physical gradients *** the contact area expands,the heat exchange is enhanced and the global heat flux intensity increases.(iii)The global TNE intensity reduces with the decreasing of physical gradients and increase with the increasing of TNE area.(iv)The nonequilibrium area increases as the fluid interface is elongated and is widened because of the dissipation and/or diffusion.

关键词： Kelvin-Helmholtz instability thermodynamic nonequilibrium effect viscous stress discrete boltzmann method

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Nonequilibrium kinetics effects in Richtmyer–Meshkov instability and reshock processes

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Communications in Theoretical Physics 2023年第11期75卷 99-114页

作者： Yiming Shan Aiguo Xu Lifeng Wang Yudong Zhang National Key Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China National Key Laboratory of Shock Wave and Detonation Physics Institute of Fluid PhysicsChina Academy of Engineering PhysicsMianyang 621900China Center for Applied Physics and Technology MOE Key Center for High Energy Density Physics SimulationsCollege of EngineeringPeking UniversityBeijing 100871China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China School of Mechanics and Safety Engineering Zhengzhou UniversityZhengzhou 450001China

Kinetic effects in the inertial confinement fusion ignition process are far from *** this work,we study the Richtmyer-Meshkov instability and reshock processes by using a two-fluid discrete boltzmann *** work begins by interpreting the experiment conducted by Collins and Jacobs(2002,*** Mech.464,113-136).It shows that the shock wave causes substances in close proximity to the substance interface to deviate more significantly from their thermodynamic equilibrium *** thermodynamic non-equilibrium(TNE)quantities exhibit complex but inspiring kinetic effects in the shock process and behind the shock *** kinetic effects are detected by two sets of TNE *** first set includes∣Δ_(2)^(*)∣,∣Δ_(3,1)^(*),∣Δ_(3)^(*)∣,and∣Δ_(4,2)^(*)∣,which correspond to the intensities of the non-organized momentum Flux(NOMF),Non-Organized Energy Flux(NOEF),the flux of NOMF and the flux of *** four TNE measures abruptly increase in the shock *** second set of TNE quantities includes■_(NOMF),■_(NOEF)and■_(sum),which denote the entropy production rates due to NOMF,NOEF and their summation,*** mixing zone is the primary contributor to■_(NOEF),while the flow field region outside of the mixing zone is the primary contributor to■_(NOMF).Additionally,each substance exhibits different behaviors in terms of entropy production rate,and the lighter fluid has a higher entropy production rate than the heavier fluid.

关键词： Richtmyer-Meshkov instability discrete boltzmann method nonequilibrium kinetics effects

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A discrete boltzmann model with symmetric velocity discretization for compressible flow

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Chinese Physics B 2023年第11期32卷 374-382页

作者：林传栋孙笑朋苏咸利赖惠林方晓 Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China School of Mathematics and Statistics the Key Laboratory of Analytical Mathematics and Applications(Ministry of Education)Fujian Key Laboratory of Analytical Mathematics and Applications(FJKLAMA)and Center for Applied Mathematics of Fujian Province(FJNU)Fujian Normal UniversityFuzhou 350117China

A discrete boltzmann model(DBM) with symmetric velocity discretization is constructed for compressible systems with an adjustable specific heat ratio in the external force field. The proposed two-dimensional(2D) nine-velocity scheme has better spatial symmetry and numerical accuracy than the discretized velocity model in literature [Acta Aerodyn. Sin.40 98108(2022)] and owns higher computational efficiency than the one in literature [Phys. Rev. E 99 012142(2019)].In addition, the matrix inversion method is adopted to calculate the discrete equilibrium distribution function and force term, both of which satisfy nine independent kinetic moment relations. Moreover, the DBM could be used to study a few thermodynamic nonequilibrium effects beyond the Euler equations that are recovered from the kinetic model in the hydrodynamic limit via the Chapman–Enskog expansion. Finally, the present method is verified through typical numerical simulations, including the free-falling process, Sod’s shock tube, sound wave, compressible Rayleigh–Taylor instability,and translational motion of a 2D fluid system.

关键词： discrete boltzmann method compressible flow nonequilibrium effect kinetic method

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Unsteady detonation with thermodynamic nonequilibrium effect based on the kinetic theory

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Communications in Theoretical Physics 2023年第7期75卷 132-144页

作者： Xianli Su Chuandong Lin Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

In this paper,unsteady detonation is simulated and investigated from the viewpoint of kinetic *** deviations of the velocity distribution function from the equilibrium state are studied in the evolution of *** has been discovered that the characteristics of the deviation around the detonation wave are significantly different from those in the post-wave ***,the kinetic moments of the reaction term have been simulated,verified and analyzed in *** addition,the reaction manifestation is defined to describe the global effects of kinetic moments due to chemical *** is interesting to find that there are three types of periodic oscillations of the reaction manifestation during the evolution of the unsteady *** the fast Fourier transform,it can be seen that the reaction manifestation is mainly composed of several signal ***,the impact of rate constants of the two-step reaction scheme on the reaction manifestation is studied,and the influence of chemical heat is investigated as well.

关键词： unsteady detonation chemical reaction kinetic theory discrete boltzmann method

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Kinetic modeling of multiphase fow based on simplified Enskog equation

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Frontiers of physics 2020年第6期15卷 133-145页

作者： Yu-Dong Zhang Ai-Guo Xu Jing-Jiang Qiu Hong-Tao Wei Zung Hang Wei School of Mechanics and Safety Engineering Zhengzhou UniversityZhengzhou 450001China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsP.O.Bor 8009-26Beijing 100088China Center for Applied Physics and Technology MOE Key Center for High Energy Density Physics SimulationsCollege of EngineeringPeking UniversilyBeifing 100871China

A new kinetic model for multiphase flow was presented under the framework of the discrete boltzmann method(DBM).Significantly different from the previous DBM,a bottom-p approach was adopted in this *** effects of molecular size and repulsion potential were described by the Enskog collision model;the attraction potential was obtained through the mean field approximation *** molecular interactions,which result in the non-ideal equation of state and surface tension,were directly introduced as an external force *** typical benchmark problems,including Couette flow,two-phase coexistence curve,the Laplace law,phase separation,and the collision of two droplets,were simulated to verify the ***,for two types of droplet collisions,the strengths of two non-equilibrium ffcts,D*2 and D*3,defined through the second and third order non-conserved kinetic moments of(f-feq),are comparatively investigated,where f(feq)is the(equilibrium)distribution *** is interesting to find that during the collision process,D*2is always significantly larger than D*3,D*2 can be used to identify the different stages of the collision process and to distinguish different types of *** modeling method can be directly extended to a *** model for the case where the non-equilibrium pffect is strong,and the linear constitutive law of viscous stress is no longer valid.

关键词： multiphase flow discrete boltzmann method Enskog equation non-equilibrium charac-teristics

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