A Wall-Modeled RANS-SA Approach for Unstructured Grids

Abstract

In this paper, we present a wall model based upon a modified version of the Spalart-Allmaras turbulence model. Unlike typical wall models, this method avoids the need to query the interior solution by utilizing solution information solely at the boundary, making it well-suited for unstructured grids and facilitating adjoint consistent discretizations-key features that enable mesh adaptation and higher-order finite element methods. This wall-modeling method is formulated to lessen the near-wall grid resolution requirements by, below the log layer, making the eddy viscosity approach a constant, non-zero value and both the velocity and SA working variable become approximately linear. Using this new wall-modeling method, the impacts of output-based mesh adaptation and higher-order methods are assessed and compared to standard RANS-SA. It is shown that this new wall-modeling approach results in accurate predictions of quantities of interest such as aerodynamic coefficients, surface pressure, and skin friction compared with RANS-SA, while requiring substantially less near-wall grid.