Licentiate seminar

Turbulence modeling using automated code generation applied to asymmetric diffuser flow

Defendant Main Advisor Extra Advisor Date
Johan Ohlsson Arne Johansson Gustav Amberg 2002-06-14

Lars Davidson, Chalmers

Evaluation committee


A versatle tool for testing turbulence models, based in highly automated code generation, was developed andapplied to the case of a plane asymmetric diffuser. The computational code contains a fractional step form of the Reynolds averaged Navier-Stokes equations and two different turbulence models, oth based on low Reynolds number K-omega formulations. The versions consist of one standard eddy viscosity model and one EARSM description of the Reynolds stress anisotropy. The flow through an asymmetric diffuser with diffuser angle 10 degrees was calculated using the code generated from the automated procedure. The results agree well with earlier calculations and measurements. A split of the inverse time scale omega was derived and introduced, removing the problem of singular behavior at solid walls. The wall normal distance needed in low Re-terms is obtained from a wall normal distance function that is computed in a mesh independent fashion.