A new wall function strategy for complex turbulent flows

Wall functions are widely used and offer significant computational savings compared with low-Reynolds-number formulations. However, existing schemes are based on assumed near-wall profiles of velocity, turbulence parameters, and temperature which are inapplicable in complex, nonequilibrium flows. A new wall function has therefore been developed which solves boundary-layer-type transport equations across a locally defined subgrid. This approach has been applied to a plane channel flow, an axisymmetric impinging jet, and flow near a spinning disc using linear and nonlinear k-ε turbulence models. Computational costs are an order of magnitude less than low-Reynolds-number calculations, while a clear improvement is shown in reproducing low-Re predictions over standard wall functions.