Laminar-To-Turbulent Boundary Layer Prediction Using an Alternative to the Laminar Kinetic Energy Approach

This paper presents a new model concept for prediction of boundary layer transition using a linear eddy-viscosity RANS approach. It is a single-point, physics-based method that adopts an alternative to the Laminar Kinetic Energy (LKE) framework. The model is based on a description of the transition process previously discussed by Walters (2009). The version of the model presented here uses the k-ω SST model as the baseline, and includes the effects of transition through one additional transport equation for v2. Here v2 is interpreted as the energy of fully turbulent, 3D velocity fluctuations, while k represents the energy of both fully turbulent and pre-transitional velocity fluctuations. This modelling approach leads to slow growth of fluctuating energy in the pre-transitional region and relaxation towards a fully turbulent model result downstream of transition. Simplicity of the formulation and ease of extension to other baseline models are two potential advantages of the new method. An initial version of the model has been implemented as a UDF subroutine in the commercial CFD code FLUENT and tested for canonical flat plate boundary layer test cases with different freestream turbulence conditions.