Direct numerical simulations of a turbulent boundary layer in an adverse pressure gradient

Direct numerical simulations (DNS) of the Navier-Stokes equations has been carried out with the objective of studying a turbulent boundary layer in an adverse pressure gradient (APG). Two APG cases has been simulated as well as one zero pressure gradient case (ZPG). The program uses spectral methods and utilizes the 'fringe method'. The simulations start with a laminar boundary layer at the inflow which is tripped by a random volume force trip near the wall. Self-similarity is obtained and different scalings are investigated. Two approaches to the analysis of the turbulent boundary layer equations found in the literature are compared. In this work we conclude that the nonlinear equations are required in order to obtain mean flow characteristics in agreement with the DNS. The analysis of turbulent statistics gives some hints to the mechanism of separation and the proper modeling required for APG boundary layers.