The simulation of unsteady transonic flow and the stability of a transonic boundary layer

A modified “triple-deck” model is proposed to investigate free unsteady viscid-inviscid interaction at transonic velocities. The modification of the model is the inclusion of the singular term of the transonic expansion, thanks to which the Lin-Reissner-Tsien equation can be refined and a more accurate description given of unsteady and non-linear phenomena. The modified model is used to consider the stability of the boundary layer interacting with an unsteady inviscid flow at transonic velocities. It is shown that the modified model enables one to take into account an additional perturbation, which escapes consideration when the classical triple-deck model is used.