Real-time Simulation of Aero-optical Distortions Due to Air Density Fluctuations at Supersonic Speed

Abstract

Aero-optical distortions produced by supersonic and hypersonic boundary layers were extensively experimentally studied using wind tunnels and CFD techniques in the last decades. But on the other hand, implementations of visual simulations of shock phenomenon have been given signi cantly less-attention. Moreover there is not an openly available simulation model of aero-optical distortions due to shock waves that can be used for ight simulators and games. We present a novel approach to simulate aero-optical distortions due to shock waves generated by a supersonic jet by considering the physics background of the shock phenomenon. While exploring the prevalent physics theories on shock waves, three main types of shock waves have been identi ed: normal shock, bow shock and oblique shock. From those, the shock waves generated by a supersonic jet are called oblique shock waves. The optical distortion is simulated by calculating the index of refraction for oblique shock waves. The refractive index for the shock wave was calculated, by considering the mean characteristics of supersonic ows. Ray tracing is a good technique to simulate refraction in higher quality. But the computer cost is considerably high. Thus this simulation is implemented using environment mapping techniques in OpenGL. Even though the ow characteristics are not uniform across the shock wave the results shows that this approach is a better way to simulate aero-optical distortions in real time.