Testing a Novel Transition Model for Mixing Layers with DNS Data

We propose to test a new transition-sensitized RANS model in the linear disturbance limit,

considering shear (Kelvin-Helmholtz) and buoyant (Rayleigh-Taylor) instabilities. Notably, the

model includes equations for the full Reynolds-stress tensor, deviating from the common practice

of transition models, which simulate only the transport of turbulent kinetic energy. This allows

for the exact closure of shear-production terms in the Reynolds-stress transport equations. The

new model also includes an explicit closure for the pressure-diffusion term, which is normally

neglected, but is shown to be critical in transition. In order to test the model, we compare

solutions to the specific forms of the equations for pure Rayleigh-Taylor and Kelvin-Helmoltz

instabilities with data from direct numerical simulation (DNS) for the same cases, using initial

conditions derived from linear stability theory. The results of these comparisons will both speak

to the validity of the transition model and provide guidance for potential modifications.