论文标题
高速可压缩流的离散玻尔兹曼建模，具有不同平衡的深度
Discrete Boltzmann modeling of high-speed compressible flows with various depths of non-equilibrium
论文作者
论文摘要
非平衡高速可压缩流呈现在工程和科学中的富裕应用。随着热力学非平衡（TNE）的加深，需要分布功能的高阶非固定动力学矩来捕获流量状态和进化过程的主要特征。基于椭圆形统计Bhatnagar-krook模型，离散的Boltzmann模型（DBMS）考虑了考虑各种阶（从第一个到第六阶）的效应的各种效应，以研究各种深度的流量。具体而言，首先，使用两种类型的一维黎曼问题和COUETTE流程来显示模型分别捕获具有零级和一阶TNE效应的大流量结构的能力。然后，使用直接模拟蒙特卡洛给出的冲击波结构用于验证模型在分子平均自由路径水平上捕获细胞结构的能力。此外，我们专注于两种碰撞流体的度。一个五个组件向量$ \ mathbf {s} _ {tne} =（τ，δ\ mathbf {u}，Δt，Δt，\ bm {δ_{2}^{*}}}}}，\ \ \ \ \ \ \ bm {Δ_发现从各种角度获得的优势不同。这些发现表明，仅关注Navier-Stokes中出现的几个动力学矩的不足，随着离散性和偏离热力学平衡的程度而增加。最后，模拟了二维游离射流，以表明，为了获得令人满意的流体动力量，DBM至少应包括至三阶TNE效应。
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 statistical Bhatnagar-Gross-Krook model, Discrete Boltzmann Models (DBMs) that consider various orders (from the first up to the sixth order) of TNE effects are developed to study flows in various depths of TNE. Specifically, at first, two types of one-dimensional Riemann problems and a Couette flow are used to show the model's capability to capture large flow structures with zero-order and first-order TNE effects, respectively. Then, a shock wave structure given by Direct simulation Monte Carlo is used to verify the model's capability to capture fine structures at the level of mean free path of molecules. Further, we focus on the TNE degree of two colliding fluids. A five-component vector $\mathbf{S}_{TNE} = (τ, Δ\mathbf{u}, ΔT, \bm{Δ_{2}^{*}},\bm{Δ_{3,1}^{*}})$ is introduced to roughly characterize the TNE degree. It is found that the TNE strengths obtained from various perspectives are different. These findings demonstrate that the inadequacy of focusing only on the few kinetic moments appearing in Navier-Stokes increases with the degree of discreteness and deviation from thermodynamic equilibrium. Finally, a two-dimensional free jet is simulated to indicate that, to obtain satisfying hydrodynamic quantities, the DBM should include at least up to the third-order TNE effects.
