Approach to Model Boundary-Layer Suction in Transition Transport Models

Abstract

Transition transport models have reached some maturity in predicting laminar-turbulent transition in numerical simulations of natural laminar flow aircraft. However, little is known about the applicability of these models to cases involving boundary-layer suction. This work demonstrates that state-of-the-art transition transport models are not suited to capture the effect of suction on laminar-turbulent transition due to Tollmien-Schlichting instabilities. Therefore, a nonlocal modification of the Simple-AHD transition criterion is proposed based on the equivalence of suction and pressure gradient. Simulation results with the modified criterion are assessed based on the numerical test case of an ideal flat plate as well as the experimental reference case of a flat plate in the DNW-NWB wind tunnel. The proposed criterion captures the effect of suction consistently, similar to transition prediction based on linear stability theory. Furthermore, the use of an effective turbulence intensity, which depends on the suction rate, is shown to improve the prediction.