Tollmien-Schlichting wave

A Tollmien-Schlichting wave is a disturbance wave that exists when viscous laminar flow in a channel is disturbed. The wave grows in amplitude due to the destabilizing effects of the no-slip conditions at the boundaries, and viscous effects in the bulk of the fluid. Similar waves are also observed in thin-films of two-phase flow, where the wave develops in the bulk of the film and thus destabilizes the interface separating the two phases.