Vortex ring-shear layer vortices interaction

Interaction between a vortex ring and shear layer vortices was simulated by the three-dimensional vortex blob method. The purpose of this research is clarifying interaction between a vortex ring and shear layer vortices, and is also the basic research of active control of the shear layer by introducing the self-propelling vortex ring from outside of the shear layer. Interaction of the vortex ring is effective in enhancing the local growth of the shear layer. Numerical simulation was performed in order to clarify the circulation ratio between the vortex ring and the shear layer vortex tube which promote the interaction between a vortex ring and shear layer vortices most. In the case of circulation ratio Γ_R/Γ_F of 1.0, shear layer vortices and the vortex ring interact strongly. Large vortices were generated by amalgamation between the shear layer vortices and the vortex ring. The vorticity thickness attains a maximum when circulation ratio Γ_R/Γ_F is 1.0. However, enhancement of the growth of the shear layer saturated when the ratio exceeds about 1.5. This is because the vortex ring which has large circulation passes through the shear layer.