Abstract

A vortex ring impinging on a three-dimensional bump is studied using Large Eddy Simulation (LES) for a Reynolds number Re = 4×10⁴ based on the initial diameter and translational speed of the vortex ring. The evolution of vortical structures are investigated and an array of flow phenomena are discovered, such as the generation and deformation of secondary vortex ring, formation of loop-like vortices, interaction of vortex rings and the instability and breakdown of vortical structures. The total enstrophy of the flow reasonably elucidates some typical phases of flow evolution. Based on the Fourier analysis of the vertical vorticity, the azimuthal instabilities of the primary vortex ring are studied. Furthermore, the mechanism of vorticity generation on the bump surface has been revealed based on analysis of the boundary vorticity flux.

Keywords:

Azimuthal instability, large eddy simulation, vortical structure,

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Competing interests

The authors have no competing interests.

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