Wall functions and boundary layer response to pulsating and oscillating turbulent channel flows

Some limitations of the classical Wall-Function approach for the near-wall boundary layer treatment in LES and URANS are presented for isothermal oscillating and pulsating channel flows. Despite their simple geometry, pulsating and oscillating flows are interesting unsteady flow test cases representative of many industrial components. A special attention will be focused on the unsteady wallshear stress prediction since it is also an indirect measure of the unsteady wall-heat transfer. A correct evaluation of the unsteady wall heat transfer is in fact critical, for example, in combustion chamber applications when flow unsteadiness due to flame instability occurs and in general in each unsteady flow situation where thermo-acoustic phenomena play an important role.