标题： 高速流动模拟中UGKWP方法的自适应准则与波粒分解修正 显示英文标题

标题： Adaptive criterion and modification of wave-particle decomposition in UGKWP method for high-speed flow simulation

摘要： 得益于在离散空间中直接建模物理定律以及自动分解流体动力学波和粒子的能力，统一气体动理论波粒（UGKWP）方法在各种多尺度物理问题上展现出显著优势，例如高超声速流动、等离子体输运和辐射输运。 为了实现高速流动模拟中更合适且高效的波粒分解，并增强其在剧烈尺度变化区域中的性能，在本研究中，我们探讨了尺度自适应准则并对UGKWP方法的通量演化进行了修改。 具体而言，除了UGKWP方法的时间相关分布函数自然考虑的时间视角外，还利用了来自空间和梯度两个额外的准则来识别局部尺度，从而减少描述近平衡微观气体分布函数时粒子的计算消耗。 此外，对应于统一气体动理论方案（UGKS）时间积分通量中的系数，流体动力学波的演化被修改得更加符合粒子行为，这对于不同单元内尺度发生剧烈变化时尤为重要。 通过一系列测试案例验证了自适应UGKWP方法的性能，包括在多个入口Knudsen数下圆柱周围的高超声速流动、细长腔体上的高超声速流动、高超声速流场中侧喷射冲击以及三维高超声速$70^{\circ}$钝头锥体带圆柱支杆的流动。 显示英文摘要

摘要： Benefitting from the direct modeling of physical laws in a discretized space and the automatic decomposition of hydrodynamic waves and particles, the unified gas-kinetic wave-particle (UGKWP) method offers notable advantages in various multiscale physics, such as hypersonic flow, plasma transport and radiation transport. Aiming at achieving a more suitable and efficient wave-particle decomposition in high-speed flow simulation and enhancing the performance in the drastic scale variation region, in this work, the scale adaptive criterion is studied and the flux evolution of UGKWP method is modified. Specifically, besides the perspective of time which is naturally considered in the time-dependent distribution function of UGKWP method, two more criteria from views of space and gradient are utilized to identify the local scale, and to reduce the computational consumption of particles on describing the near-equilibrium microscopic gas distribution function. Moreover, corresponding to the coefficients in the time integration flux of unified gas-kinetic scheme (UGKS), the evolution of hydrodynamic wave is modified to be more consistent with particles, which is essential when the scale changes intensely in different cells. A variety of test cases are conducted to validate the performance of the adaptive UGKWP method, including hypersonic flows around a cylinder at multiple inflow Knudsen numbers, hypersonic flow over a slender cavity, side-jet impingement on hypersonic flow and three-dimensional hypersonic flows over a $70^{\circ}$ blunted cone with a cylindrical sting.