Overset meshes for incompressible flows: On preserving accuracy of underlying discretizations

作     者：Sharma, Ashesh Ananthan, Shreyas Sitaraman, Jayanarayanan Thomas, Stephen Sprague, Michael A. 

作者机构：Natl Renewable Energy Lab Golden CO 80401 USA Parallel Geometr Algorithms LLC Sunnyvale CA USA 

出 版 物：《JOURNAL OF COMPUTATIONAL PHYSICS》 (计算物理学杂志)

年 卷 期：2021年第428卷

页      面：109987-109987页

核心收录：

学科分类：07[理学] 0812[工学-计算机科学与技术（可授工学、理学学位）] 0702[理学-物理学] 

基　　金：U.S. Department of Energy Office of Science [17-SC-20-SC] National Nuclear Security Administration [17-SC-20-SC] U.S. Department of Energy (DOE) [DE-AC36-08GO28308] DOE Office of Energy Efficiency and Renewable Energy 

主　　题：Computational fluid dynamics Unstructured meshes Chimera grid Overset Additive Schwarz Wind energy 

摘      要：This study on overset meshes for incompressible-flow simulations is motivated by accurate prediction of wind farm aerodynamics involving large motions and deformations of components with complex geometry. Using first-order hyperbolic and elliptic equation proxies for the incompressible Navier-Stokes (NS) equations, we investigate the influence of information exchange between overset meshes on numerical performance where the underlying discretization is second-order accurate. The first aspect of information exchange surrounds interpolation of solution where we examine Lagrange and point-cloud-based interpolation for creating constraint equations between overset meshes. To maintain overall second-order accuracy, higher-order interpolation is required for elliptic problems, but linear interpolation is sufficient for hyperbolic problems in first-order form. Higher order point-cloud-based interpolation provides a pathway to maintaining accuracy in unstructured meshes, but at higher complexity. The second aspect of information exchange focuses on comparing the approaches of overset single system (OSS) and overset Additive Schwarz (OAS) for coupling the linear systems of the overlapping meshes. While the former involves a single linear system, in the latter the discrete linear systems are solved separately, and solving the global system is accomplished through outer iterations and sequential information exchange in a Jacobi fashion. For the test cases studied, accuracy for hyperbolic problems is maintained by performing two outer iterations, whereas many outer iterations are required for elliptic systems. The order-of-accuracy studies explored here are critical for verifying the overset-mesh coupling algorithms used in engineering simulations. Accuracy of these simulations themselves is, however, quantified using engineering quantities of interest such as drag, power, etc. Consequently, we conclude with numerical experiments using NS equations for incompressible flows wher