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To study simultaneously the hydrodynamic and thermodynamic behaviors in compressible flow systems with spherical or cylindrical symmetry, we present a theoretical framework for constructing Discrete Boltzmann Model(DBM) with spherical or…

Statistical Mechanics · Physics 2014-04-01 Aiguo Xu , Guangcai Zhang , Chuandong Lin

Combining discrete and continuous data is an important capability for generative models. We present Discrete Flow Models (DFMs), a new flow-based model of discrete data that provides the missing link in enabling flow-based generative models…

Machine Learning · Statistics 2024-06-07 Andrew Campbell , Jason Yim , Regina Barzilay , Tom Rainforth , Tommi Jaakkola

We present a series of three-dimensional discrete Boltzmann (DB) models for compressible flows in and out of equilibrium. The key formulating technique is the construction of discrete equilibrium distribution function through inversely…

Fluid Dynamics · Physics 2018-03-06 Yanbiao Gan , Aiguo Xu , Guangcai Zhang , Huilin Lai

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…

Fluid Dynamics · Physics 2022-09-07 Dejia Zhang , Aiguo Xu , Yudong Zhang , Yanbiao Gan , Yingjun Li

An implicit high-order discontinuous Galerkin (DG) method is developed to find steady-state solution of rarefied gas flow described by the Boltzmann equation with full collision operator. In the physical space, velocity distribution…

Computational Physics · Physics 2019-01-08 Wei Su , Peng Wang , Yonghao Zhang , Lei Wu

A new kinetic model is proposed where the equilibrium distribution with bounded support has a range of velocities about two average velocities in 1D. In 2D, the equilibrium distribution function has a range of velocities about four average…

Fluid Dynamics · Physics 2023-08-15 Shashi Shekhar Roy , S. V. Raghurama Rao

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…

Computational Physics · Physics 2022-03-24 Yudong Zhang , Aiguo Xu , Jingjiang Qiu , Hongtao Wei , Zung-Hang Wei

The discrete velocity method (DVM) is a powerful framework for simulating gas flows across continuum to rarefied regimes, yet its efficiency remains limited by existing quadrature rules. Conventional infinite-domain quadratures, such as…

Fluid Dynamics · Physics 2025-10-23 Lu Wang , Lingyun Deng , Guanqing Wang , Hong Liang , Jiangrong Xu

The paper develops a novel motion model, called Generalized Multi-Speed Dubins Motion Model (GMDM), which extends the Dubins model by considering multiple speeds. While the Dubins model produces time-optimal paths under a constant speed…

Robotics · Computer Science 2025-04-14 James P. Wilson , Shalabh Gupta , Thomas A. Wettergren

We provide a theoretical analysis for end-to-end training Discrete Flow Matching (DFM) generative models. DFM is a promising discrete generative modeling framework that learns the underlying generative dynamics by training a neural network…

Machine Learning · Computer Science 2025-09-29 Maojiang Su , Mingcheng Lu , Jerry Yao-Chieh Hu , Shang Wu , Zhao Song , Alex Reneau , Han Liu

In this paper, we propose the ultra-discrete optimal velocity model, a cellular-automaton model for traffic flow, by applying the ultra-discrete method for the optimal velocity model. The optimal velocity model, defined by a differential…

Cellular Automata and Lattice Gases · Physics 2009-05-23 Masahiro Kanai , Shin Isojima , Katsuhiro Nishinari , Tetsuji Tokihiro

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…

Statistical Mechanics · Physics 2023-09-01 Aiguo Xu

In this paper, we present a new model to simulate the formation, evolution, and break up of a thin film of fluid flowing over a curved surface. Referred to as the discrete droplet method (DDM), the model captures the evolution of thin fluid…

Fluid Dynamics · Physics 2022-10-20 Anand S Bharadwaj , Joerg Kuhnert , Stephane P. A. Bordas , Pratik Suchde

Thermodynamic nonequilibrium effects play a central role in momentum and energy transport in compressible flows. In conventional BGK kinetic models, the relaxation time $\tau$ is taken as a constant, which neglects the dependence of the…

Fluid Dynamics · Physics 2026-05-19 Demei Li , Zhongyi He , Huilin Lai , Yanbiao Gan , Hailong Liu , Pengfei Lin

In this paper, we present an improved framework of the spectral-based Discrete Dislocation Dynamics (DDD) approach introduced in [1,2], that establishes a direct connection with the continuum Field Dislocation Mechanics (FDM) approach. To…

Computational Physics · Physics 2018-04-04 Nicolas Bertin

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…

Fluid Dynamics · Physics 2018-06-06 Yanbiao Gan , Aiguo Xu , Guangcai Zhang , Yudong Zhang , Sauro Succi

The Bhatnagar-Gross-Krook (BGK) model of the Boltzmann equation allows for efficient flow simulations, especially in the transition regime between continuum and high rarefaction. However, ensuring efficient performances for multiscale…

Fluid Dynamics · Physics 2025-05-09 Félix Garmirian , Marcel Pfeiffer

The gradient discretisation method (GDM) is a generic framework for designing and analysing numerical schemes for diffusion models. In this paper, we study the GDM for the porous medium equation, including fast diffusion and slow diffusion…

Numerical Analysis · Mathematics 2020-04-02 Jerome Droniou , Kim-Ngan Le

Simulations of the discrete Boltzmann Bhatnagar-Gross-Krook (BGK) equation are an important tool for understanding fluid dynamics in non-continuum regimes. Here, we introduce a discontinuous Galerkin finite element method (DG-FEM) for…

Fluid Dynamics · Physics 2024-06-19 Karthik Ganeshan , David M. Williams

An implicit multiscale method with multiple macroscopic prediction for steady state solutions of gas flow in all flow regimes is presented. The method is based on the finite volume discrete velocity method (DVM) framework. At the cell…

Computational Physics · Physics 2020-02-19 Ruifeng Yuan , Chengwen Zhong