Session Ci - Vortex Dynamics.
ORAL session, Sunday, November 23
309, Moscone Center
An LES scheme is developed for simulating turbulent flows with concentrated large-scale vorticity. The scheme combines an adaptive, viscous, three-dimensional vortex element method with a dynamic eddy viscosity model of the sub-filter scale stresses. Dynamic implementation of sub-filter scale model relies on determining model coefficients through test-filtering of Lagrangian particle representation of the filtered vorticity field.
The vorticity-based dynamic model is examined using a priori tests based on direct numerical simulations of forced homogeneous, isotropic turbulence. These tests show a fair correlation of the turbulence model with the sub-filter scale convection of vorticity. Moreover, the computed value of the dynamic model coefficient is in agreement with predictions based on enstrophy balances. The Lagrangian LES scheme is then applied to the simulation of the evolution of a single vortex ring in free space, and of the co-axial collision of two vortex rings.