二次元噴流の遷移過程 : 第1報, 渦度分布と渦の移動速度

抄録

The coherent structure dynamics was experimentally investigated in a two-dimensional jet. The fundamental velocity fluctuation modes, i.e., the symmetrical and antisymmetrical modes, were excited acoustically in the jet. Conditional sampling was employed and vorticity contours were calculated from ensemble-averaged velocity components, and the mean velocity at the center of the vortex, the peak value of vorticity, and trajectory of the coherent vortex were educed. The peak position of the coherent vorticity component moved almost parallel to the jet axis in both cases of the excited jets. The convection velocity of the vortex was almost constant throughout the linear interaction and the nonlinear interaction regions independent of the local mean velocity at the center of the vortex . Furthermore, the convection velocity was larger than the local mean velocity throughout the linear interaction regions.