Aiguo Xu

• PhD
• Professor at Institute of Applied Physics and Computational Mathematics

In this mini-review we summarize the progress of Lattice Boltzmann(LB) modeling and simulating compressible flows in our group in recent years. Main contents include (i) Single-Relaxation-Time(SRT) LB model supplemented by additional viscosity, (ii) Multiple-Relaxation-Time(MRT) LB model, and (iii) LB study on hydrodynamic instabilities. The former...

Detonation is a kind of self-propagating supersonic combustion where the chemical reaction is rapid and violent under an extreme condition. The leading part of a detonation front is pre-shocked by a strong shock wave propagating into the explosive and triggering chemical reaction. The combustion system can be regarded as a kind of chemical reactive...

A 2-dimensional discrete Boltzmann model for combustion is presented. Mathematically, the model is composed of two coupled discrete Boltzmann equations for two species and a phenomenological equation for chemical reaction process. Physically, apart from the macroscopic behaviors described by a reactive Navier–Stokes model, this model presents also...

A discrete Boltzmann model (DBM) is developed to investigate the hydrodynamic and thermodynamic non-equilibrium (TNE) effects in phase separation process. The interparticle forces drive changes and the gradient force, induced by gradients of macroscopic quantities, oppose them. In this paper we investigate the interplay between them by providing de...

To probe both the Mechanical Non-Equilibrium (MNE) and Thermodynamic Non-Equilibrium (TNE) in the combustion procedure, a two-dimensional Multiple-Relaxation-Time (MRT) version of the Lattice Boltzmann Kinetic Model(LBKM) for combustion phenomena is presented. The chemical energy released in the progress of combustion is dynamically coupled into th...

Supersonic flow simulations encounter challenges in threefold: trans-scale modeling, numerical stability and complex field analysis, due to their inherent nonlinear, nonequilibrium and multiscale characteristics. The discrete Boltzmann method (DBM) provides a multiscale kinetic modeling framework and a set of analysis tools to capture complex discr...

This study investigates the complex kinetics of thermodynamic nonequilibrium effects (TNEs) and their relative importance during the development of the Kelvin–Helmholtz instability (KHI) using high-order discrete Boltzmann models (DBMs). First, the capabilities and differences among various discrete velocity sets in capturing TNEs and distribution...

Three-dimensional (3D) high-speed compressible flow is a typical nonlinear, nonequilibrium, and multiscale complex flow. Traditional fluid mechanics models, based on the quasi-continuum assumption and near-equilibrium approximation, are insufficient to capture significant discrete effects and thermodynamic nonequilibrium effects (TNEs) as the Knuds...

The Kelvin–Helmholtz Instability (KHI) with and without external magnetic fields is computationally investigated based on the Discrete Boltzmann Method (DBM). The maximum local Knudsen number in the system is up to more than 0.06. Simultaneously, the density correction induced by the second-order Knudsen number effects near some interfaces is up to...

This study investigates the droplet coalescence mechanisms and the interplay between various thermodynamic non-equilibrium (TNE) effects under isothermal and non-isothermal conditions kinetically. The main findings include: (1) Coalescence initiation and cut-through mechanisms: In non-isothermal conditions, the temperature rise caused by the releas...

The Richtmyer-Meshkov (RM) instability occurs when a perturbed interface between two fluids undergoes impulsive acceleration due to a shock wave. In this paper, a numerical investigation of the RM instability during the reshock process is conducted using the two-component discrete Boltzmann method. The influence of reflection distance on the RM ins...

Supersonic flow is a typical nonlinear, nonequilibrium, multiscale, and complex phenomenon. This paper applies discrete Boltzmann method/model (DBM) to simulate and analyze these characteristics. A Burnett-level DBM for supersonic flow is constructed based on the Shakhov-BGK model. Higher-order analytical expressions for thermodynamic nonequilibriu...

Shock waves are typical non-equilibrium phenomena in nature and engineering, driven by hydrodynamic non-equilibrium (HNE) and thermodynamic non-equilibrium (TNE) effects. However, the mechanisms underlying these non-equilibrium effects are not fully understood. This study develops the discrete Boltzmann method (DBM) by directly discretizing velocit...

This study investigates the complex dynamics of thermodynamic nonequilibrium effects (TNEs) and their relative importance during the development of the Kelvin-Helmholtz instability (KHI) using high-order discrete Boltzmann models (DBMs). First, the capabilities and differences among various discrete velocity sets in capturing TNEs and distribution...

Three-dimensional (3D) high-speed compressible flow is a typical nonlinear, nonequilibrium, and multiscale complex flow. Traditional fluid mechanics models, based on the quasi-continuum assumption and near-equilibrium approximation, are insufficient to capture significant discrete effects and thermodynamic nonequilibrium effects (TNEs) as the Knuds...

The present study employs a combination of numerical and analytical techniques to examine the detonation flows of explosives containing compressible inert particles. A two-phase numerical model incorporating the compressibility of the particles is developed, and the two-phase detonation process is simulated under the Lagrangian framework, where the...

A multi-relaxation-time discrete Boltzmann model for compressible non-ideal gases with adjustable specific heat ratio is proposed, and the impact of surface tension on Rayleigh-Taylor instability (RTI) is investigated from two perspectives: macroscopic and non-equilibrium characteristics. In terms of physical cognition, (1) it is found that there a...

Early studies on Rayleigh-Taylor instability (RTI) primarily relied on the Navier-Stokes (NS) model. As research progresses, it becomes increasingly evident that the kinetic information that the NS model failed to capture is of great value for identifying and even controlling the RTI process; simultaneously, the lack of analysis techniques for comp...

The mean azimuthal flow of puff, a key structure of the subcritical transition in pipe flow, is studied numerically and theoretically in this Letter. It is revealed that the mean azimuthal velocities (MAVs) are governed by the least stable azimuthal modes at the far downstream and upstream, respectively. At the upstream near-wall region, the statis...

The study of macro continuous flow has a long history. Simultaneously, 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 science. However, due to absence of suitable methods, the understanding of mesoscale be...

The thermodynamic non-equilibrium (TNE) effects and the relationships between various TNE effects and entropy production rate, morphology, kinematics, and dynamics during two initially static droplet coalescences are studied in detail via the discrete Boltzmann method. Temporal evolutions of the total TNE strength D ¯ * and the total entropy produc...

In this paper, a discrete Boltzmann method (DBM) for plasma kinetics is proposed and further used to investigate the non-equilibrium characteristics in Orszag–Tang (OT) vortex and Richtmyer–Meshkov instability (RMI) problems. The construction of DBM mainly considers two aspects. The first is to build a physical model with sufficient capability to c...

A two-fluid discrete Boltzmann model with a flexible Prandtl number is formulated to study the shock–bubble interaction (SBI). This paper mainly focuses on the viscous effects on morphological and thermodynamic non-equilibrium (TNE) characterizations during the SBI process. Due to the rapid and brief nature of the SBI process, viscosity has a relat...

In micro- and nanoscale channels, where the characteristic scale approaches or falls below the mean free path between gas molecules, flow characteristics exhibit pronounced discontinuity. In such scenarios, continuum-based models are inadequate, and adopting kinetic models based on statistical mechanics becomes imperative for accurately describing...

We briefly introduce several fundamental problems that cause the creation of Discrete Boltzmann modeling and analysis Method(DBM), corresponding solutions, the relationship and difference between DBM and traditional fluid modeling and other kinetic methods, and some applications of DBM and discrete/non-equilibrium effects.

Kinetic effects in the inertial confinement fusion ignition process are far from clear. In this work, we study the Richtmyer-Meshkov instability (RMI) and reshock processes by using a two-fluid discrete Boltzmann method (DBM). The work begins from interpreting the experiment conducted by Collins and Jacobs [J. Fluid Mech. 464,113-136(2002)]. It shows...

The viscous effects on the interaction between a shock wave and a two-dimensional cylindrical bubble are investigated based on the discrete Boltzmann method (DBM). Besides some interesting Hydrodynamic Non-Equilibrium (HNE) behaviors, some relevant Thermodynamic Non-Equilibrium (TNE) behaviors are carefully studied. It is found that the viscosity c...

A discrete Boltzmann model (DBM) for plasma kinetics is proposed. The DBM contains two physical functions. The first is to capture the main features aiming to investigate and the second is to present schemes for checking thermodynamic non-equilibrium (TNE) state and describing TNE effects. For the first function, mathematically, the model is compos...

Specific-heat ratio effects on the interaction between a planar shock wave and a two-dimensional heavy-cylindrical bubble are studied by the discrete Boltzmann method (DBM). Snapshots of schlieren images and evolutions of characteristic scales, being consistent with experiments, are obtained. The corresponding Hydrodynamic Non-Equilibriums and rela...

The aim of this paper is twofold: the first aim is to formulate and validate a multi-scale discrete Boltzmann method (DBM) based on density functional kinetic theory for thermal multiphase flow systems, ranging from continuum to transition flow regime; the second aim is to present some new insights into the thermo-hydrodynamic non-equilibrium (THNE...

The two-dimensional Rayleigh–Taylor Instability (RTI) under multi-mode perturbation in compressible flow is probed via the Discrete Boltzmann Modeling (DBM) with tracers. The distribution of tracers provides clear boundaries between light and heavy fluids in the position space. Besides, the position-velocity phase space offers a new perspective for...

A Discrete Boltzmann Model(DBM) based on the Shakhov model for detonation is proposed. Compared with the DBM based on the Bhatnagar-Gross-Krook (BGK) model, the current model has a flexible Prandtl numbers and consequently can be applied to a much wider range of detonation phenomena. Besides the Hydrodynamic Non-Equilibrium (HNE) behaviors usually...

Nonequilibrium kinetic effects are widespread in fluid systems and might have a significant impact on the inertial confinement fusion ignition process, and the entropy production rate is a key factor in accessing the compression process. In this work, we study the Richtmyer-Meshkov instability (RMI) and the reshock process by a two-fluid discrete B...

The thermodynamic nonequilibrium (TNE) effects in a coalescence process of two initially static bubbles under thermal conditions are investigated by a discrete Boltzmann model. The spatial distributions of the typical nonequilibrium quantity, i.e., nonorganized momentum fluxes (NOMFs), during evolutions are investigated in detail. The density-weigh...

The non-equilibrium high-speed compressible flows present wealthy applications in engineering and science. With the deepening of Thermodynamic Non-Equilibrium (TNE), higher-order non-conserved kinetic moments of the distribution function are needed to capture the main feature of the flow state and evolution process. Based on the ellipsoidal statist...

The two-dimensional Rayleigh-Taylor instability (RTI) in compressible flow with intermolecular interactions is probed via the discrete Boltzmann method. The effects of interfacial tension, viscosity, and heat conduction are investigated. It is found that the influences of interfacial tension on the perturbation amplitude, bubble velocity, and two k...

The effects of initial perturbations on the Rayleigh–Taylor instability (RTI), Kelvin–Helmholtz in�stability (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 i...

The non-equilibrium high-speed compressible flows present wealthy applications in engineering and science. With the deepening of Thermodynamic Non-Equilibrium (TNE), higher-order non-conserved kinetic moments of the distribution function are needed to capture the main feature of the flow state and evolution process. Based on the ellipsoidal statist...

The Rayleigh-Taylor Instability (RTI) under multi-mode perturbation in compressible flow is probed via the Discrete Boltzmann Modeling (DBM) with tracers. The distribution of tracers provides clear boundaries between light and heavy fluids in the position space. Besides, the position-velocity phase space offers a new perspective for understanding t...

A Discrete Boltzmann Model(DBM) based on the Shakhov model for detonation is proposed. Compared with the DBM based on the Bhatnagar–Gross–Krook (BGK) model, the current model has a flexible Prandtl numbers and consequently can be applied to a much wider range of detonation phenomena. Besides the Hydrodynamic Non-Equilibrium (HNE) behaviors usually...

The Thermodynamic Non-Equilibrium (TNE) effects in the coalescing process of two initially static bubbles under thermal conditions are investigated by a Discrete Boltzmann Model (DBM). The spatial distributions of the typical none-quilibrium quantity, i.e., the Non-Organized Momentum Fluxes (NOMF) during evolutions are investigated in detail. The d...

We propose a new model for the crown evolution after a single drop impacts on a thin film. In contrast with the existing models that mainly focus on the status of well-developed crown or the bottom radius evolution, multiple features are provided in our model, including the temporal evolution of the crown radius, height, velocity, and the character...

Plasma shock waves widely exist and play an important role in high-energy-density environment, especially in the inertial confinement fusion. Due to the large gradient of macroscopic physical quantities and the coupled thermal, electrical, magnetic, and optical phenomena, there exist not only hydrodynamic non-equilibrium (HNE) effects but also stro...

The Rayleigh-Taylor Instability (RTI) in compressible flow with inter-molecular interactions is probed via the Discrete Boltzmann Method (DBM). The effects of interfacial tension, viscosity and heat conduction are investigated. It is found that the influences of interfacial tension on the perturbation amplitude, bubble velocity, and two kinds of en...

Numerical solving of the Boltzmann equation is a very demanding task. Fortunately, in most instances, such exploration can be restricted to a low-dimensional linear manifold of phase-space, spanned by a suitable subset of low order kinetic moments of the Boltzmann distribution. The identification of the most suitable manifold is problem-specific. I...

Slip flow is a common phenomenon in micro-/nano-electromechanical systems. It is well known that the mass and heat transfers in slip flow show many unique behaviors, such as the velocity slip and temperature jump near the wall. However, the kinetic understanding of slip flow is still an open problem. This paper first clarifies that the Thermodynami...

In the paper, 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 effe...

Traditional computational fluid dynamics based on solving Navier-Stokes equations has achieved great success in many fields, but it has also encountered new bottlenecks and challenges in aerospace, microfluidic and other fields. The reasons can be divided into two aspects: (A) the problem of physical modeling; (B) the numerical accuracy and stabili...

Nowadays, improving the thermal efficiency of internal combustion engine (IC Engine) has becoming increasingly essential. In this paper, the influences of thermal barrier coating (TBC) on the near wall combustion and pollutant distribution in Gasoline/Diesel RCCI (Reactivity Controlled Compression Ignition) and GCI (Gasoline Compression Ignition) c...

Fractured natural gas hydrate (NGH) reservoirs are widely tested all over the world. Existence of fractures will aggravate the basin-scale heterogeneity in both NGH distribution and seepage properties and, therefore, inevitably challenge some of our former understanding on gas production. However, gas productivities of the fractured NGH reservoirs...

Plasma shock waves widely exist and play an important role in high-energy-density environment, especially in the inertial confinement fusion. Due to the large gradient of macroscopic physical quantities and the coupled thermal, electrical, magnetic and optical phenomena, there exist not only hydrodynamic non-equilibrium (HNE) effects, but also stro...

Rayleigh–Taylor-instability (RTI) induced flow and mixing are of great importance in both nature and engineering scenarios. To capture the underpinning physics, tracers are introduced to make a supplement to discrete Boltzmann simulation of compressible RTI flows. By marking two types of tracers with different colors, the tracer distribution provid...

The development of lattice gas model to discrete Boltzmann method is briefly introduced for modeling multiphase complex fluid systems. Based on the basic principles of statistical physics, the Boltzmann equation is given through the idea of coarse-grained modeling. The physical images of progressively refined measurements contained in the Chapman-E...

Droplet impingement is a widespread phenomenon in nature and industrial production. Different from the problem of light drop/wall impact, which has been investigated early and sufficiently, few researches are found on the dynamic behavior and modeling of heavy drop impingement, which is widely existed in the field of plasma spray, 3D printing and e...

A multiple-relaxation-time discrete Boltzmann model (DBM) is proposed for multicomponent mixtures, where compressible, hydrodynamic, and thermodynamic nonequilibrium effects are taken into account. It allows the specific heat ratio and the Prandtl number to be adjustable, and is suitable for both low and high speed fluid flows. From the physical si...

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-up approach was adopted in this model. The effects of molecular size and repulsion potential were described by the Enskog collision model; the attraction potential was obtained thr...

A two-fluid Discrete Boltzmann Model (DBM) for compressible flows based on the ellipsoidal statistical Bhatnagar–Gross–Krook is presented. The model has a flexible Prandtl number or specific heat ratio. Mathematically, the model is composed of two coupled Discrete Boltzmann Equations (DBEs). Each DBE describes one component of the fluid. Physically...

In this paper, the coupled Rayleigh–Taylor–Kelvin–Helmholtz instability (RTI, KHI, and RTKHI, respectively) system is investigated using a multiple-relaxation-time discrete Boltzmann model. Both the morphological boundary length and thermodynamic non-equilibrium (TNE) strength are introduced to probe the complex configurations and kinetic processes...

In this paper, the coupled Rayleigh-Taylor-Kelvin-Helmholtz instability(RTI, KHI and RTKHI, respectively) system is investigated using a multiple-relaxation-time discrete Boltzmann model. Both the morphological boundary length and thermodynamic nonequilibrium (TNE) strength are introduced to probe the complex configurations and kinetic processes. I...

A new kinetic model for multiphase flow was presented under the framework of discrete Boltzmann method (DBM). Significantly different from the previous DBM, a bottom-up approach was adopted in this model. The effects of molecular size and repulsion potential were described by the Enskog collision model; the attraction potential was obtained through...

A 2-fluid Discrete Boltzmann Model(DBM) for compressible flows based on Ellipsoidal Statistical Bhatnagar-Gross-Krook(ES-BGK) is presented. The model has flexible Prandtl number and specific heat ratio. Mathematically, the model is composed of two coupled Discrete Boltzmann Equations(DBE). Each DBE describes one component of the fluid. Physically,...

Based on the framework of our previous work [H.L. Lai et al., Phys. Rev. E, 94, 023106 (2016)], we continue to study the effects of Knudsen number on two-dimensional Rayleigh–Taylor (RT) instability in compressible fluid via the discrete Boltzmann method. It is found that the Knudsen number effects strongly inhibit the RT instability but always eno...

Horizontal flow of discrete objects through a bottleneck is prevalent and important in nature and industry. In this paper, we experimentally investigate the frictional effect of the bottom wall on the flow rate of granular particles passing through an aperture on a conveyor belt, since the bottom wall is always assumed to be trivial and the issue r...

A multiple-relaxation-time discrete Boltzmann model (DBM) is proposed for multicomponent mixtures, where compressible, hydrodynamic, and thermodynamic nonequilibrium effects are taken into account. It allows the specific heat ratio and the Prandtl number to be adjustable, and is suitable for both low and high speed fluid flows. From the physical si...

Rayleigh-Taylor-instability induced flow and mixing are of great importance both in nature and engineering scenarios. To capture the underpinning physics, one-way coupled particles are introduced to make a Lagrangian tracking supplement to the discrete Boltzmann simulation. Detailed morphological information of the flow field and thermodynamic none...

Several different kinds of criteria for non-equilibrium phase separation to discriminate the two stages, the spinnodal decompostion (SD) and domain growth (DG), are compared and further investigated. The characteristic domain size and morphological function present two geometric criteria. Both of them can only provide rough estimations for the cros...

We investigate the effects of viscosity and heat conduction on the onset and growth of Kelvin–Helmholtz instability (KHI) via an efficient discrete Boltzmann model. Technically, two effective approaches are presented to quantitatively analyze and understand the configurations and kinetic processes. One is to determine the thickness of mixing layers...

The understanding of flow behavior in rough fractures is essential for many engineering activities. When the aperture of a rough fracture approaches the mean free path of fluid molecules, the microflow effect, sometimes also referred to relative rarefaction effect, relative discrete effect or non-equilibrium effect, becomes pronounced. It was found...

Microchannel flow shows a fascinating background on a lot of engineering problems. In order to shed a light on the effect of the surface morphology of microchannels on fluid flow, differently shaped and arranged artificial elements constitute channels with different morphology and numerical simulation based on lattice Boltzmann method is conducted....

Entropy production during the process of thermal phase-separation of multiphase flows is investigated by means of a discrete Boltzmann kinetic model. The entropy production rate is found to increase during the spinodal decomposition stage and to decrease during the domain growth stage, attaining its maximum at the crossover between the two. Such be...

A one-dimensional discrete Boltzmann model for detonation simulation is presented. Instead of numerical solving Navier-Stokes equations, this model obtains the information of flow field through numerical solving specially discretized Boltzmann equation. Several classical benchmarks including Sod shock wave tube, Colella explosion problem, and one-d...

A one-dimensional discrete Boltzmann model for detonation simulation is presented. Instead of numerical solving Navier-Stokes equations, this model obtains the information of flow field through numerical solving specially discretized Boltzmann equation. Several classical benchmarks including Sod shock wave tube, Colella explosion problem, and one-d...

During this presentation, we've given our understanding of the flow behavior in rough fractures. Including the direct simulation results and theoretical analysis.

We investigate the effects of viscosity and heat conduction on the onset and growth of Kelvin- Helmholtz instability (KHI) via an efficient discrete Boltzmann model. Both hydrodynamic and thermodynamic nonequilibrium (TNE) manifestations, as well as morphological characterizations are extracted to analyze and understand the configurations and kinet...

Several different kinds of criteria for non-equilibrium phase separation to discriminate the two stages, the spinnodal decompostion (SD) and domain growth (DG), are compared and further investigated. The characteristic domain size and morphological function present two geometric criteria. Both of them can only provide rough estimations for the cros...

The entropy production of thermal phase separation is investigated base on the multiphase flow discrete Boltzmann model. First, the relationship between entropy production rate and the non-equilibrium quantities is established. Two mechanisms, the non-organised energy fluxes (NOEF) and the non-organised moment fluxes (NOMF), are responsible for the...

We use a discrete Boltzmann model (DBM) to simulate the multi-mode Rayleigh-Taylor instability (RTI) in a compressible flow. This DBM is physically equivalent to a Navier-Stokes model supplemented by a coarse-grained model for thermodynamic nonequilibrium behavior. The validity of the model is verified by comparing simulation results of Riemann pro...

Discrete Boltzmann model (DBM) is a type of coarse-grained mesoscale kinetic model derived from the Boltzmann equation. Physically, it is roughly equivalent to a hydrodynamic model supplemented by a coarse-grained model for the relevant thermodynamic non-equilibrium (TNE) behaviours. The Navier-Stokes (NS) model is a traditional macroscopic hydrody...

Discrete Boltzmann model (DBM) is a type of coarse-grained mesoscale kinetic model derived from the Boltzmann equation. Physically, it is roughly equivalent to a hydrodynamic model supplemented by a coarse-grained model for the relevant thermodynamic non-equilibrium (TNE) behaviours. The Navier-Stokes (NS) model is a traditional macroscopic hydrody...

The two-dimensional Richtmyer-Meshkov Instability(RMI) system and the coexisting system combined with Rayleigh-Taylor Instability(RTI) are simulated with a multiple-relaxation time discrete Boltzmann model. It is found that, for the RMI system, the correlation between globally averaged non-organized energy flux and nonuniformity of temperature is n...

A general framework for constructing discrete Boltzmann model for non-equilibrium flows based on the Shakhov model is presented. The Hermite polynomial expansion and a set of discrete velocity with isotropy are adopted to solve the kinetic moments of discrete equilibrium distribution function. Such a model possesses both an adjustable specific heat...

The two-dimensional Richtmyer-Meshkov Instability(RMI) system and the coexisting system combined with Rayleigh-Taylor Instability(RTI) are simulated with a multiple-relaxation time discrete Boltzmann model. It is found that, for the RMI system, the correlation between globally averaged non-organized energy flux and nonuniformity of temperature is n...

To kinetically model implosion and explosion related phenomena, we present a theoretical framework for constructing Discrete Boltzmann Model(DBM) with spherical symmetry in spherical coordinates. To this aim, a key technique is to use \emph{local} Cartesian coordinates to describe the particle velocity in the kinetic model. Thus, the geometric effe...

To kinetically model implosion and explosion related phenomena, we present a theoretical framework for constructing Discrete Boltzmann Model(DBM) with spherical symmetry in spherical coordinates. To this aim, a key technique is to use \emph{local} Cartesian coordinates to describe the particle velocity in the kinetic model. Thus, the geometric effe...

The rarefied effect of gas flow in microchannel is significant and cannot be well described by traditional hydrodynamic models. It has been known that discrete Boltzmann model (DBM) has the potential to investigate flows in a relatively wider range of Knudsen number because of its intrinsic kinetic nature inherited from Boltzmann equation. It is cr...

We present a general framework for constructing trans-scale discrete Boltzmann models (DBMs) for high-speed compressible flows ranging from continuum to transition regime. This is achieved by designing a higher-order discrete equilibrium distribution function which satisfies additional nonhydrodynamic kinetic moments. In order to characterize the t...

We present a general framework for constructing trans-scale \emph{discrete Boltzmann models} (DBMs) for high-speed compressible flows ranging from continuum to transition regime. This is achieved by designing a higher-order discrete equilibrium distribution function which satisfies additional nonhydrodynamic kinetic moments. In order to characteriz...

A discrete Boltzmann model (DBM) is proposed to probe the Rayleigh-Taylor instability (RTI) in two-component compressible flows. Each species has a flexible specific-heat ratio and is described by one discrete Boltzmann equation (DBE). Independent discrete velocities are adopted for the two DBEs. The collision and force terms in the DBE account for...