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arXiv 2103.14890math.NAcs.NA
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非结构网格上Boltzmann模型的IMEX时间推进高阶有限体积格式

High order finite volume schemes with IMEX time stepping for the Boltzmann model on unstructured meshes

Walter Boscheri, Giacomo Dimarco

摘要:

本文提出了一族求解完整Boltzmann方程的时空高阶有限体积格式。速度空间采用离散纵标法近似,碰撞积分采用谱方法求解。空间重构是通过对描述系统状态的分布函数在任意形状的封闭控制体上进行积分来实现的。与其他重建方法相比,这种方法允许保持紧凑的模板尺寸,这是一个显着的属性,由于相当大的计算资源的需求,在动力学方程的上下文中。全离散,然后通过结合以前的相空间近似高阶隐式显式(IMEX)龙格库塔格式。这些方法保证了渐近状态的稳定性、准确性和保持性。Boltzmann模型与简单的弛豫型动力学模型(如BGK)的比较,提出了玻尔兹曼方程捕获不同的物理解的能力。收敛的理论顺序在不同的制度和方法进行了测试,在几个标准的二维基准问题的数值测量与直接模拟蒙特卡罗结果比较。文章最后给出了一个绕NACA 0012翼型的亚音速和超音速流的原型工程问题。所有的测试用例都在多个线程上运行MPI并行化,从而使所提出的方法适用于并行分布式内存的超级计算机。

英文摘要:

In this work, we present a family of time and space high order finite volume schemes for the solution of the full Boltzmann equation. The velocity space is approximated by using a discrete ordinate approach while the collisional integral is solved by spectral methods. The space reconstruction is realized by integrating the distribution function, describing the state of the system, over arbitrary shaped and closed control volumes using a Central Weighted ENO (CWENO) technique. Compared to other reconstruction methods, this approach permits to keep compact stencil sizes which is a remarkable property in the context of kinetic equations due to the considerable demand of computational resources. The full discretization is then obtained by combining the previous phase-space approximation with high order Implicit-Explicit (IMEX) Runge Kutta schemes. These methods guarantee stability, accuracy and preservation of the asymptotic state. Comparisons of the Boltzmann model with simpler relaxation type kinetic models (like BGK) is proposed showing the capability of the Boltzmann equation to capture different physical solutions. The theoretical order of convergence is numerically measured in different regimes and the methods are tested on several standard two-dimensional benchmark problems in comparison with Direct Simulation Monte Carlo results. The article ends with a prototype engineering problem consisting of a subsonic and a supersonic flow around a NACA 0012 airfoil. All test cases are run with MPI parallelization on several threads, thus making the proposed methods suitable for parallel distributed memory supercomputers.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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