SPARTACUS: An open-source unified stochastic particle solver for the simulation of multiscale nonequilibrium gas flows
收藏资源简介：
Recently, a unified stochastic particle (USP) method [14] has been developed for the simulation of multiscale nonequilibrium gas flows. Compared with the conventional stochastic particle methods, such as the direct simulation Monte Carlo (DSMC) method, USP can be applied with much larger time steps and cell sizes as it couples the effects of particle movements and collisions. To extend the applicability of USP to complex nonequilibrium gas flows, we develop a USP solver referred to as SPARTACUS within the framework of SPARTA, which is a widely used software based on the DSMC method for the simulation of rarefied gas flows. Inheriting from SPARTA, SPARTACUS is parallelized with the message passing interface (MPI), and it is open-source under the GNU General Public License (GPL) and released in an online repository with essential documentation, tutorial examples, and benchmark cases. To evaluate the performance of SPARTACUS, the test cases cover from one to three dimensional flows with a wide range of the Knudsen number and Mach number, including Couette flow, lid-driven cavity flow, hypersonic flow past a cylinder, and supersonic flow around a blunt body. The results obtained by SPARTACUS in the rarefied and continuum regimes are in good agreement with DSMC and computational fluid dynamics (CFD) results, respectively. Moreover, SPARTACUS has significant computational efficiency advantage over traditional DSMC solvers, especially for three-dimensional nonequilibrium gas flows. In addition, SPARTACUS shows comparable parallel efficiency with SPARTA, so it is promising to be applied with high performance computing for the simulation of complex multiscale gas flows encountered in engineering problems.
近年来，针对多尺度非平衡气体流动模拟，研究者提出了统一随机粒子（unified stochastic particle, USP）方法[14]。相较于直接模拟蒙特卡洛（direct simulation Monte Carlo, DSMC）等传统随机粒子方法，USP方法可采用更大的时间步长与网格单元尺寸，因其耦合了粒子运动与碰撞过程。为拓展USP方法在复杂非平衡气体流动中的适用性，我们在基于DSMC方法开发的通用稀薄气体流动模拟软件SPARTA的框架内，搭建了一款名为SPARTACUS的USP求解器。SPARTACUS继承了SPARTA的特性，采用消息传递接口（message passing interface, MPI）实现并行计算，且遵循GNU通用公共许可证（GNU General Public License, GPL）开源，已在在线代码仓库发布，并附带完整文档、教程示例与基准测试案例。为验证SPARTACUS的性能，本研究选取覆盖1至3维的流动场景作为测试算例，涉及宽范围克努森数与马赫数的工况，包含库埃特流、驱动腔流、圆柱高超音速绕流以及钝体超音速绕流。SPARTACUS在稀薄流区与连续流区得到的计算结果，分别与DSMC方法与计算流体力学（computational fluid dynamics, CFD）结果吻合良好。此外，相较于传统DSMC求解器，SPARTACUS具备显著的计算效率优势，尤其在三维非平衡气体流动模拟中表现突出。同时，SPARTACUS与SPARTA的并行效率相当，因此在面向工程问题中的复杂多尺度气体流动的高性能计算模拟场景中，该求解器具备良好的应用前景。
