Direct Numerical Simulations Of Axisymmetric Density Currents.

Abstract

Three dimensional direct numerical simulations are presented for axisymmetric density
currents using the Boussinesq approximation for small density difference. Three Gr numbers
are investigated (105, 1.5×106 and 107) in order to identify differences in the flow structure
and dynamics, and to compare with planar density currents.
The simulations are performed using a fully de-aliased pseudospectral method. The simulated
flows present the main features observed in experiments for the large Gr numbers. The
front location and velocity computed show that the Fr relation used to close the box model and
shallow water models for density currents must be corrected to account for Gr and geometrical
dependencies.