基于联合流体粒子方法的高速非平衡流模拟

Simulation of high-speed non-equilibrium flows via the joint hydrodynamics-particle method

  • 摘要: 针对高速流动中的显著非平衡特性,本文基于联合流体粒子(joint hydrodynamics-particle, JHP)方法,对典型高速流动开展数值模拟研究。该方法采用随机粒子描述无碰撞迁移过程,并通过积分解框架结合单元平均碰撞时间和全局推进步长引入竞争机制,实现宏观Navier-Stokes(N-S)方程与介观粒子输运的耦合,能够准确刻画局部强非平衡流动特征。为验证该方法对高速非平衡流动的模拟能力,选取马赫数20条件下的一维激波结构和二维高速圆柱绕流,以及马赫数5条件下的钝楔绕流作为典型算例。通过与统一气体动理学格式(UGKS)及统一气体动理学波粒法(UGKWP)结果对比,验证了JHP方法在温度、速度等宏观量分布及流场结构预测方面的准确性。进一步与N-S方程结果对比,并引入局部Knudsen数对流场中非平衡区域的空间分布特征进行分析,发现相较于传统宏观方程,JHP能够更准确地捕捉激波层、近壁区及尾迹区等局部强非平衡区域的流动特征。研究表明,高速流场中的非平衡效应具有显著的区域性特征,并对流场演化产生重要影响。在钝楔绕流算例中,JHP方法的计算时间约为参考方法(IUGKS)的37.9%,内存消耗约为2.5%,表明该方法可为高速非平衡流的高效高精度模拟提供有效手段。

     

    Abstract: Targeting the pronounced non-equilibrium characteristics of high-speed flows, this study conducted numerical simulations of typical high-speed flows based on the joint hydrodynamics–particle (JHP) method. The method employed stochastic particles to describe collisionless transport, and a competition mechanism was introduced within an integral solution framework through the coupling of the cell-averaged collision time and the global time step. This enabled a unified coupling between the macroscopic Navier–Stokes (N-S) equations and mesoscopic particle transport, allowing accurate resolution of locally strong non-equilibrium features. To validate the applicability of the method for high-speed non-equilibrium flows, three benchmark cases were selected: a one-dimensional shock structure and a high-speed flow over a circular cylinder at Mach 20, as well as a high-speed blunt-wedge flow at Mach 5. Comparisons with the unified gas-kinetic scheme (UGKS) and the unified gas-kinetic wave–particle (UGKWP) method demonstrated that the JHP method achieves high accuracy in predicting macroscopic quantities, including temperature and velocity distributions, as well as overall flow structures. Further comparisons with N-S solutions, combined with local Knudsen number analysis, revealed the spatial distribution of non-equilibrium regions within the flow field. Compared with conventional macroscopic approaches, the JHP method more accurately captures flow features in regions with strong non-equilibrium effects, such as the shock layer, near-wall region, and wake. These results indicate that non-equilibrium effects in high-speed flows exhibit pronounced spatial heterogeneity and significantly influence flow evolution. In the blunt wedge flow case, the computational time of the JHP method is approximately 37.9% of that of the reference method (IUGKS), and its memory consumption is about 2.5%, indicating that the method provides an efficient and high-fidelity approach for the simulation of hypersonic non-equilibrium flows.

     

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