Direct numerical and statistical simulation of turbulent boundary layer flows with pressure gradient

A zonal grid approach has been developed as a means to reduce the large number of grid points required for direct numerical simulation (DNS) of boundary layers. The case of a boundary layer flow with zero pressure gradient shows that computational resources can be saved by zonal DNS compared to a full fine grid DNS and that the accuracy of the results is increased as compared to a completely coarse grid. The zonal grid approach is also used for DNS of boundary layer flow with adverse pressure gradient. DNS results are compared with experimental data. In order to evaluate the performance of existing turbulence models, RANS simulations have been performed for the same boundary layer under adverse pressure gradient. Several models, ranging from two-equation models to Reynolds stress transport models have been tested and the results are compared with DNS and experimental data.