Session: 05-02-02 CFD Methods

Paper Number: 87742

87742 - A Wall-Modeled Large Eddy Simulation Method for High-Order Spectral Element Solvers 

A new method for implementation of wall-modeled large eddy simulation (WMLES) is presented for use with high-order spectral element methods. This class of numerical method presents unique challenges for wall modeling, specifically related to the application of appropriate wall boundary conditions and the specification of modeled fluxes in the near-wall region. The new method addresses these difficulties through the use of an assumed wall function velocity profile in the first near-wall elements, which is used to determine the wall shear stress as well as appropriate pseudo-fluxes which are summed and implemented as source terms at each grid point located in the near-wall elements. Furthermore, the method ensures that the mean velocity field is C1 continuous at the interface between the wall-modeled and the outer region. Simulations are performed using the spectral element solver Nek5000 and results are compared to high-fidelity DNS, LES, and experimental data. The test cases considered are fully developed channel flow, backward facing step flow, and flow over a two-dimensional ramp. Several variations are investigated including varying mesh sizes and different subgrid stress models for the baseline LES method used. The results show that the new wall function methodology produces results in close agreement with more fully resolved LES, with a savings in computational cost that improves with increasing Reynolds number.The results are also found to be superior to recently published results using WMLES for finite element methods. The new wall-modeling strategy can potentially lead to significant savings in computational effort for scale-resolving simulations using specral element numerical methods. 

Presenting Author: D. Keith Walters University of Arkansas