Large eddy simulations of aero-optical effects in a turbulent boundary layer

Abstract

Large eddy simulations (LESs) of aero-optical effects in a turbulent boundary layer have been carried out at two different Mach numbers (0.9 and 2.3) for two different wall boundary conditions (adiabatic and isothermal). Moreover, in the adiabatic case, LESs were performed on two different meshes. First, aerodynamic fields are proved to compare favourably with theoretical and experimental results. Once validated, the characteristics of the boundary layer allow us to obtain information concerning optical beam degradation. The density field is then used to compute the phase distortion induced by turbulent fluctuations on a coherent optical beam. The Mach number effect on the phase distortion is evaluated by means of these computations and the link between index-of-refraction fluctuations and phase distortion is discussed. Moreover, LES allows us to study optical models and the validity of their assumptions. Finally, LES is proved to be considered as a reference tool to evaluate phase distortion.