An effect of initial disturbance on spatial development of a two-dimensional jet at a low reynolds number

Abstract

When the jet Reynolds number is slightly higher than the Reynolds number which a whole two-dimensional jet maintains laminar, a flapping motion causes in the jet. Before the jet generates laminar-turbulent transition, it moves asymmetrically. A numerical simulation of the two-dimensional jet was carried out to research effect of an initial disturbance on a flapping motion. When white noise is uniformly added at the slit, the disturbance does not grow. If white noise is asymmetrically added at the slit, the disturbance rapidly grows and introduces the flapping motion. The asymmetrical disturbances are selected from natural disturbances in the actually two-dimensional jets at low Reynolds number, so that the flapping motion is formed in the two-dimensional jets.