Spatial development of disturbances in plane Poiseuille flow: a direct numerical simulation using a commercial CFD code

Spatial development of small amplitude disturbances in plane Poiseuille flow is investigated numerically using a commercial CFD code (CFX 4.2). Small amplitude Tollmien–Schlichting (TS) waves known from an Orr–Sommerfeld analysis are superimposed as initial conditions on a fully developed laminar channel flow. The downstream spatial disturbances are calculated on the basis of the full Navier–Stokes equations (NSE). Results are compared to calculations based on the Orr–Sommerfeld equations (OSE). In a second step the thermal energy equation is solved in addition to the NSE to investigate the temperature effects and especially the development of temperature disturbances. A certain delay in the development of these disturbances is found which is due to a thermal receptivity mechanism. These results again are compared to OSE calculations.