Wall scaling and wall models for complex turbulent flows

The near wall behaviour of complex turbulent flows is investigated by dimensional considerations and a priori investigations. We consider separated incompressible and compressible flows. In incompressible turbulent flows, it is found that the flow in the immediate vicinity of the wall is dependent on two parameters, based on wall friction and local pressure gradient, respectively. In compressible turbulent flows, a third parameter based on the wall heat flux is relevant for the flow profiles in vicinity of the wall. While in the viscous sub-layer, an exact law of the wall can be formulated, the buffer and log-layer is dependent on empirical formulations. The significance of the wall scaling is shown by carefully carried out Direct Numerical Simulations and Large-Eddy Simulations of incompressible and compressible separated flows.