Theoretical analyses on flapping motion of submerged turbulent plane jets

Although the flapping oscillatory motion is organized, its effect on the mean flows of turbulent plane jets is similar to the effect of turbulence. Therefore, the close relation for the stress due to flapping-induced velocity components is assumed to be similar to the relation for the turbulent Reynolds stress, and the similarity theory applicable for mean flows of turbulent plane jets is extended to that of unstable flapping turbulent plane jets. The results show the effect of flapping motion on mean flows can be regarded as two folds: one is to enhance the mixing by flapping-induced Reynolds stress and the other is to modify the effective advection. The results from similarity analyses are in good agreement with the experimental data.