Modeling of Laminar-Turbulent Transition for High Freestream Turbulence

To simulate transitional skin friction or heat transfer, the conditionally averaged Navier-Stokes equations are used. To describe the diffusion of freestream turbulence into the boundary layer and the intermittent laminar-turbulent flow behavior during transition, a turbulence weighting factor τ is used. A transport equation is presented for this τ-factor including convection, diffusion, production, and sink terms. In combination with the conditioned Navier-Stokes equations, this leads to an accurate calculation of flow characteristics within the transitional layer. The method is validated on transitional skin friction and heat transfer measurements, respectively on a flat plate and in a linear turbine cascade.