Updates to Implicit Edge-Based Gradient Methods

Hiroaki Nishikawa

NASA NTRS · 20230015557

Updates to Implicit Edge-Based Gradient Methods

Abstract

In this paper, we report updates to the implicit edge-based gradient methods originally introduced in [H. Nishikawa, AIAA Paper 2020-3048, 2020]. First, we clarify the relationship between gradient accuracy and truncation error and show that the quadratic method involves a free parameter. Then, we provide a complete description and a simplified matrix form of the implicit gradient systems including a consistent boundary treatment, and derive a set of parameters for achieving fourth-order gradient accuracy on regular tetrahedral grids. A stability analysis is performed for a relaxation scheme used to solve the implicit gradient systems, and the result serves as a guide for choosing parameters. Numerical results are shown for accuracy verification and also for realistic inviscid flow problems in three dimensions, including flows with shock waves.

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Weighted Least-Squares Computational Fluid Dynamics Hypersonic Flow Gradient Limiters Unstructured Grids Adapted Grids

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Hiroaki Nishikawa. Updates to Implicit Edge-Based Gradient Methods. https://ntrs.nasa.gov/citations/20230015557

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