  In this study, we conduct a parametric analysis to evaluate the sensitivities
of wall-modeled large-eddy simulation (LES) with respect to subgrid-scale (SGS)
models, mesh resolution, wall boundary conditions and mesh anisotropy. While
such investigations have been conducted for attached/flat-plate flow
configurations, systematic studies specifically targeting turbulent flows with
separation are notably sparse. To bridge this gap, our study focuses on the
flow over a two-dimensional Gaussian-shaped bump at a moderately high Reynolds
number, which involves smooth-body separation of a turbulent boundary layer
under pressure-gradient and surface-curvature effects. In the simulations, the
no-slip condition at the wall is replaced by three different forms of boundary
condition based on the thin boundary layer equations and the mean wall-shear
stress from high-fidelity numerical simulation to avoid the additional
complexity of modeling the wall-shear stress. Various statistics, including the
mean separation bubble size, mean velocity profile, and dissipation from SGS
model, are compared and analyzed. The results reveal that capturing the
separation bubble strongly depends on the choice of SGS model. While
simulations approach grid convergence with resolutions nearing those of
wall-resolved LES meshes, above this limit, the LES predictions exhibit
intricate sensitivities to mesh resolution. Furthermore, both wall boundary
conditions and the anisotropy of mesh cells exert discernible impacts on the
turbulent flow predictions, yet the magnitudes of these impacts vary based on
the specific SGS model chosen for the simulation.
