Dynamics of vortex-ring/wall collisions with background rotation

We present direct numerical simulations of toroidal vortex rings interacting with a flat boundary in presence of a background rotation. It is known that, depending on the Reynolds number (the nondimensional vortex-ring strength) the separation of wall vorticity can produce secondary and tertiary rings which amplify the initial azimuthal instabilities.

In presence of background rotation, this dynamics are altered owing to the balance of angular momentum which induces faster (slower) toroidal flow within the ring cores when they shrink (expand) radially.

We study the dynamics of the collision for different rotation rates and explore all regimes, from weak rotation up to the one rotation-dominated in which the collision with the wall is inhibited and the initial impulse of the ring produces inertial waves.

The simulations are performed by integrating the Navier-Stokes equations, written in cylindrical coordinates using staggered, central, second-order accurate finite-difference discretizations.

The conde is run on the latest Nvidia GPU architectures which allow for high-resolution simulations (order 1 billion nodes) within a wall clock time less than 24 hours using a single node.