A Vortex Method for Wall Bounded Turbulent Flows

Turbulent ow in a channel is simulated using a vortex method. Smoothed vortex sheets cover the near wall region while the vorticity in the remainder of the ow is contained in convecting and stretching vortex laments. The sheet elements are convected and regridded at each time step thus enabling evaluation of their wall-normal viscous diiusion and vortex stretching using nite diierences. New laments are created during signiicant ejection events initiated by parent vortices. Chorin's hairpin removal algorithm is used as a physically based subgrid model to limit the range of resolved scales. Calculations on the order of 2000 time steps have been completed thus far. From a perturbed state, the numerical solution develops toward a self-sustained turbulent ow. An initial explosive growth in the number of new vortex structures occurs as the ow compensates for the absence of suucient spanwise vorticity in the initial conditions. Vortex production is self-limiting, however, and the ow subsequently relaxes toward a quasi-equilibrium in which new vortex lament creation occurs at only a small number of spatially intermittent locations. Preliminary statistics taken from the ongoing simulations suggest that the computational eld is approaching the correct physical state.