Grid-Adaptation for Wall-Modeled Large Eddy Simulation Using Unstructured High-Order Methods

TL;DR

This paper introduces a grid-adaptation algorithm for wall-modeled large eddy simulations using unstructured high-order methods, significantly reducing computational cost while maintaining accuracy.

Contribution

It adapts a residual-based grid adaptation method to a Discontinuous Galerkin Spectral Elements Method for unstructured grids, demonstrating improved efficiency.

Findings

Achieves up to 50% lower computational cost

Maintains comparable accuracy with fewer grid elements

Proves robustness across different flow cases

Abstract

The accuracy and computational cost of a large eddy simulation are highly dependent on the computational grid. Building optimal grids manually from a priori knowledge is not feasible in most practical use cases; instead, solution-adaptive strategies can provide a robust and cost-efficient method to generate a grid with the desired accuracy. We adapt the grid-adaptation algorithm developed by Toosi and Larsson to a Discontinuous Galerkin Spectral Elements Method (DGSEM) and show its potential on fully unstructured grids. The core of the method is the computation of the estimated modeling residual using the polynomial basis functions used in DGSEM, and the averaging of the estimated residual over each element. The final method is assessed in multiple channel flow test cases and for the transonic flow over an airfoil, in both cases making use of mortar interfaces between elements with hanging nodes. The method is found to be robust and reliable, and to provide solutions at up to 50% lower cost at comparable accuracy compared to when using human-generated grids.