Automatic Transition Prediction in a Structured Navier-Stokes Solver Using Linear Stability Theory

A structured Reynolds-Averaged Navier-Stokes solver is directly coupled to a Linear Stability Theory (LST) solver to include the effect of laminar-turbulent transition in the flow simulations. The flow-field variables of the flow solver are used to both find streamlines along which transition can be predicted and to provide the LST code with the required boundary layer profiles. Instabilities included in the analysis are of the Tollmien-Schlichting (TS) and cross-flow (CF) nature relevant to high Reynolds number flows in low turbulence environments. The coupling is fully automated and can therefore be used efficiently in the analysis and design of geometries with external flows. TU Braunschweig Sickle Wing with span-wise varying cross-flow and the Natural Laminar Flow version of the Common Research Model (CRM-NLF) are simulated under various conditions. Applications to these relevant three-dimensional test cases showcase the capability of the method to model the real flow physics. Advantages and challenges of the approach with regard to future design endeavors are discussed.