Edge-Based Viscous Method for Mixed-Element Node-Centered Finite-Volume Solvers

Yi Liu; Boris Diskin; Hiroaki Nishikawa; William K. Anderson; Gabriel C. Nastac; Eric J. Nielsen; Li Wang

NASA NTRS · 20220005528

Edge-Based Viscous Method for Mixed-Element Node-Centered Finite-Volume Solvers

Yi Liu·Boris Diskin·Hiroaki Nishikawa·William K. Anderson·Gabriel C. Nastac·Eric J. Nielsen·Li Wang

Abstract

A novel, efficient, edge-based viscous (EBV) discretization method has been recently developed, implemented in a practical, unstructured-grid, node-centered, finite-volume flow solver, and applied to viscous-kernel computations that include evaluations of meanflow viscous fluxes, turbulence-model and chemistry-model diffusion terms, and the corresponding Jacobian contributions. Initially, the EBV method had been implemented for tetrahedral grids and demonstrated multifold acceleration of all viscous-kernel computations. This paper presents an extension of the EBV method for mixed-element grids. In addition to the primal edges of a given mixed-element grid, virtual edges are introduced to connect cell nodes that are not connected by a primal edge. The EBV method uses an efficient loop over all (primal and virtual) edges and features a compact discretization stencil based on the nearest neighbors. This study verifies the EBV method and assesses its efficiency on mixed-element grids by comparing the EBV solution accuracy and iterative convergence with those of well-established solutions obtained using a cell-based viscous (CBV) discretization method. The EBV solver’s memory footprint is optimized and often smaller than the memory footprint of the CBV solver. A multifold speedup is demonstrated for all viscous-kernel computations resulting in significant reduction of the time to solutions for several benchmark mixed-element-grid computations, including simulations of a flow around NASA’s juncture-flow model and a hypersonic, chemically reacting flow around a blunt body.

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Yi Liu, Boris Diskin, Hiroaki Nishikawa, William K. Anderson, Gabriel C. Nastac, Eric J. Nielsen, Li Wang. Edge-Based Viscous Method for Mixed-Element Node-Centered Finite-Volume Solvers. https://ntrs.nasa.gov/citations/20220005528

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