S053014 速度欠損領域の不安定波によって励起した圧縮性混合層のDNS

Abstract

The spatial development of vortices in a subsonic mixing layer which have wake components is investigated numerically using two-dimensional direct numerical simulations (DNS). The mixing layer is formed by a thin flat plate and forced by normal velocity disturbances of various frequencies at the lower region of the flat plate trailing edge. The numerical results show that the growth of the disturbance induces the counter-rotating vortices in the wake like region of the mixing layer. It is found that the vortices caused by the disturbance of the frequency St=0.042 uppress development of the mixing layer. This frequency corresponds the dominant vortices period in the near downstream region of the trailing edge for non-disturbance case. This result suggests that the emission noise caused by vortex rollup or pairing in the mixing layer can be reduced by forcing with a disturbance at the lower region of the flat plate trailing edge.