Abstract: An overview of our recent numerical and experimental studies on transition between steady regular and Mach reflections of strong shock waves will be presented. The existence of the dual solution domain at high Mach numbers implies that, depending on the initial conditions, both regular and Mach reflections may be observed at the same flow parameters.
The numerical simulations confirm the hypothesis of the existence of a hysteresis of regular and Mach reflections with variation of the incident shock wave angle. Regular reflection (RR) is maintained until the shock wave angle exceeds the upper limit of its existence, where a sudden transition to Mach reflection (MR) occurs. When the shock wave angle is decreased back, the Mach reflection is maintained until the lower limit of its existence is reached.
However, the experimental data are ambiguous. In some wind tunnels the transition from RR to MR occurs at any angle inside the dual solution domain. This is usually explained by the influence of the flow disturbances, which promote the transition. However, the mechanisms of such forced transition are still not understood.
Our recent experiments performed in a "quiet" supersonic wind tunnel have shown a prominent hysteresis loop: the transition between regular and Mach reflections occurs in close agreement with theoretical predictions. The conclusion is that the interpretation of wind tunnel experiments in this problem must take into account the level of free-stream disturbances in the wind tunnel flow.
This seminar is easily accessible to persons with disabilities. For more information or for assistance, please contact the Mathematics Department at 743-3500.