Realization of Confined Turbulence Through Multiple Vortex Ring Collisions

We report a method to generate a steady, localized blob of turbulence by colliding multiple vortex rings successively. Our system supplies vorticity to a turbulent region through vortex rings, which enables us to create controlled turbulent flows far from boundaries. The state of turbulence can be controlled by altering properties of the injected rings. We present spatial structures and turbulence characteristics of the blobs by varying strength, size and shape of the vortex rings. This novel method provides an ideal system to study both generation and decay of turbulence absent from any boundary effects.