Observing production and growth of Tollmien–Schlichting waves in subsonic flat plate boundary layer via exciters-free high fidelity numerical simulation

Abstract

A numerical solution of the Navier–Stokes equations describing the instability of a two-dimensional subsonic flow about a flat plate is presented. It is obtained with the 16th-order multioperators-based scheme without introducing artificial exciters. It shows how small numerical disturbances produced by the scheme generate downstream from the leading edge a succession of wave packets formed by the Tollmien–Schlichting waves. When travelling downstream, the packets demonstrate high amplification rates and the occurrence of separation bubbles. The details of their coming into being, the spatial–temporal progress and the spectra are described.