ADVANCED COMPUTATIONAL TECHNIQUES IN STUDIES OF HYPERSONIC BOUNDARY-LAYER TRANSITION

THE OBJECTIVE OF THE PROPOSED WORK IS TO USE ADVANCED THEORETICAL AND COMPUTATIONAL TECHNIQUES FOR STUDIES OF HYPERSONIC BOUNDARY LAYER STABILITY AND TRANSITION TO TURBULENCE. THESE STUDIES WILL ENHANCE OUR UNDERSTANDING OF THE TRANSITION PHENOMENA AND THUS HELP PREDICT AND CONTROL TRANSITION WITH A HIGH DEGREE OF CONFIDENCE. TO ACHIEVE OUR GOAL, WE USE LINEAR STABILITY THEORY, SECONDARY INSTABILITY AND WEAKLY NONLINEAR THEORIES AND FULL NUMERICAL SIMULATIONS INVOLVING STATE-OF-THE-ART COMPUTATIONAL TECHNIQUES (MULTI-DOMAIN SPECTRAL COLLOCATION METHODS, HIGHER-ORDER FINITEDIFFERENCE METHODS). OF PARTICULAR INTEREST TO US IS THE INVESTIGATION OF THE EFFECT OF ADVERSE PRESSURE GRADIENT AND THE QUESTION OF NONLINEAR BREAKDOWN. A LONG-TERM GOAL IS TO COUPLE THE LINEAR AND NONLINEAR STAGES WITH RECEPTIVITY PHENOMENON IN ORDER TO DEVELOP A TRULY PREDICTIVE TECHNIQUE WHICH IS NEEDED FOR THE DESIGN OF HYPERSONIC VEHICLES.