Analysis of Stability of the Boundary Layer on a Flat Plate under a Finite-Thickness Two-Layer Compliant Coating

Abstract

Results of studying stability of the Blasius boundary layer on a two-layer compliant coating in the linear formulation are reported. The computations are based on experimental parameters of viscoelasticity of a real coating, which reveal the dependences of its elasticity modulus and loss coefficient on frequency. Parametric investigations of the influence of the coating layer thicknesses and free-stream velocity on flow stability, in particular, on the critical Reynolds number, are performed. Regions of a nonmonotonic behavior of the critical Reynolds number are found, which allow one to determine the optimal thicknesses of the upper and lower layers for intense interaction with the flow. An explanation of this effect is proposed.