SPATIAL SIMULATION OF THE INSTABILITY OF CHANNEL FLOW WITH LOCAL SUCTION BLOWING/

A direct numerical simulation was made of instability in a spatially e volving channel how. A local surface suction/blowing was imposed at th e upper wall (x/h=20). A Tollmien-Schlichting (TS) wave was superimpos ed on the laminar channel flow at the inflow. At the outflow, the buff er domain technique was applied to suppress the reflection of outgoing waves. The influence of the local suction/blowing on the linear and n onlinear 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 am plitude (0 less than or equal to A(TS)less than or equal to 2.0) on th e subcritical channel flow were scrutinized. Two regimes of the wave/f low interaction were found by varing A(S), i.e., ''monotonic'' and ''v ortex splitting'' regimes. (C) 1997 American Institute of Physics.