New Wall Function Methods for Use with Coarse Near-Wall Meshes in Turbulent Flow Computational Fluid Dynamics Simulations
Fairchilds, William Landrum
AdvisorWalters, D. Keith
A common alternative to full resolution of the near-wall region in computational fluid dynamics (CFD) simulations is the use of wall functions that decrease the mesh requirements in this region. This study presents two alternatives to current wall functions. The first method is based on numerically approximating a turbulent velocity profile using a one-dimensional subgrid contained within wall-adjacent control cells. The second method is an analytical approach similar to previous wall function methods, but this method is valid both inside and outside of the fluid boundary layer. Use of both methods allows approximation of boundary layers of varying height relative to the first layer sizing. Use of these methods allows wall adjacent primary grid sizes to vary from low-Re model sizing of y+ ≈ 1 to grid sizes of y+ ~ 1000 or more without significant loss in accuracy, and with computational costs similar to currently used wall functions.