The predictive accuracy of wall-modeled large eddy simulation is studied by
systematic simulation campaigns of turbulent channel flow. The effect of wall
model, grid resolution and anisotropy, numerical convective scheme and
subgrid-scale modeling is investigated. All of these factors affect the
resulting accuracy, and their action is to a large extent intertwined. The wall
model is of the wall-stress type, and its sensitivity to location of velocity
sampling, as well as law of the wall's parameters is assessed. For efficient
exploration of the model parameter space (anisotropic grid resolution and wall
model parameter values), generalized polynomial chaos expansions are used to
construct metamodels for the responses which are taken to be measures of the
predictive error in quantities of interest (QoIs). The QoIs include the mean
wall shear stress and profiles of the mean velocity, the turbulent kinetic
energy, and the Reynolds shear stress. DNS data is used as reference. Within
the tested framework, a particular second-order accurate CFD code (OpenFOAM),
the results provide ample support for grid and method parameters
recommendations which are proposed in the present paper, and which provide good
results for the QoIs. Notably, good results are obtained with a grid with
isotropic (cubic) hexahedral cells, with 15000 cells per δ3, where
δ is the channel half-height (or thickness of the turbulent boundary
layer). The importance of providing enough numerical dissipation to obtain
accurate QoIs is demonstrated. The main channel flow case investigated is Reτ​=5200, but extension to a wide range of Re-numbers is
considered. Use of other numerical methods and software would likely modify
these recommendations, at least slightly, but the proposed framework is fully
applicable to investigate this as well