Spatial simulation of the instability of channel flow with local suction/blowing

Abstract

A direct numerical simulation was made of instability in a spatially evolving channel how. A local surface suction/blowing was imposed at the upper wall (x/h=20). A Tollmien-Schlichting (TS) wave was superimposed on the laminar channel flow at the inflow. At the outflow, the buffer domain technique was applied to suppress the reflection of outgoing waves. The influence of the local suction/blowing on the linear and nonlinear instabilities of the flow was examined. It was found that the local suction/blowing increases the disturbance energy significantly in the interaction zone for subcritical (Re = 5000) and supercritical (Re = 10 000) cases. The effects of the blowing strength (0 less than or equal to A(s) less than or equal to 0.1) and the initial TS wave amplitude (0 less than or equal to A(TS)less than or equal to 2.0) on the subcritical channel flow were scrutinized. Two regimes of the wave/flow interaction were found by varing A(S), i.e., ''monotonic'' and ''vortex splitting'' regimes. (C) 1997 American Institute of Physics.