Eddy-viscosity wall boundary condition for wall-modeled large-eddy simulation in a finite-difference framework

We study the effect of wall boundary conditions on the statistics in a wall-modeled large-eddy simulation (WMLES) of turbulent channel flows. We consider a no-slip condition at the wall in which the wall stress is imposed by adjusting the value of the eddy viscosity at the wall and compare it with the widely used Neumann boundary condition. The results show that the type of boundary condition utilized has an impact on the statistics (e.g., mean velocity profile and turbulence intensities) in the vicinity of the wall, especially at the first off-wall grid point. Augmenting the eddy viscosity at the wall results in improved predictions of statistics in the near-wall region, which should allow the use of information from the first off-wall grid point for wall models without additional spatial or temporal filtering. This boundary condition is easy to implement and provides a simple solution to the well-known log-layer mismatch in WMLES.