Stochastic Sensitivity Analysis of the Effect of Exchange Location Height in Wall-Modeled LES
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Turbulent flows with adverse pressure gradients and separation are critical in many engineering applications. While RANS methods often lack accuracy for these complex phenomena, LES offers improved predictions at a computational cost that frequently limits its practical use. Wall-Modeled LES (WMLES) seeks to bridge this gap by modeling the near-wall region of the boundary layer, reducing computational cost while preserving much of LES accuracy. However, its reliability remains challenging in complex flows with strong pressure gradients, separation, or relaminarization. We consider herein the NASA hump flow from CFDVal2004 workshop, a well-known testcase featuring all these phenomena. Wall modeled LES are conducted with the high-order spectral element code SOD2D. Two key elements of WMLES are the wall model (WM) and the distance from the wall of the exchange location where the WM is coupled with LES. Here, we consider a conventional equilibrium model (EWM) based on Reichardt’s wall law and a wall model that accounts for non-equilibrium phenomena (NEWM), and we perform a stochastic sensitivity analysis with respect to the exchange-location height. Continuous response surfaces of the quantities of interest are obtained using generalized polynomial chaos.
