14/11/2012: On Transition Between Regular and Mach-Reflection of Shock Waves Prof. Hans Hornung


On Transition Between Regular and Mach-Reflection of Shock Waves


November 14, 2012, 16:15-17:00, ML H 44, ETH Zurich

Prof. Hans G. Hornung
Emeritus Director of GALCIT, Caltech, Pasadena, USA
 
In the late 1970’s it was discovered that the condition at which the transition occurs in steady flows is incorrectly given by nearly all gas dynamics texts. Further, the transition is hysteretic, i. e., it occurs at a different point depending on whether the shock angle is being decreased or increased. Hysteresis is always associated with a domain in which both solutions are possible. Stability arguments suggest that Mach reflection is the sta- ble configuration in the dual-solution domain, but there was considerable disagreement about this before the experiments reported here.
The background will be presented to set the scene, and new theory, simulations and new experimental results from the supersonic Ludwieg Tube at Caltech will be presented. In the latter, high-speed schlieren cinematography is used to show that zapping a regular reflection in the dual-solution domain with a laser can trip it to swing to Mach reflection. Comparisons of theoretical, computational and experimental details of this process will be presented.
 
Host: Prof. D. Poulikakos

More about the speaker: dx.doi.org/10.1016/j.paerosci.2009.10.003