Interaction of vorticity with a free surface in turbulent open channel flow
Abstract
The interaction between vorticity and a free surface, modeled as a shear free boundary is studied using a direct numerical simulation of an open channel flow at low Reynolds number. As a result of the shear free nature of the top boundary, only normal vorticity may terminate on it. The vorticity components parallel to the top boundary must go to zero as the boundary is approached. The time averaged fluctuating enstrophy balance equations are evaluated. Near the free surface the rate of production and destruction of enstrophy is set by the stretching and rotation of fluctuating vorticity by the fluctuating velocity field. Of the production terms, the three involving the stretching of vorticity along its axis are the most important, and a simple model explaining this is presented.
- Publication:
-
29th AIAA Aerospace Sciences Meeting
- Pub Date:
- January 1991
- Bibcode:
- 1991aiaa.meetQU...L
- Keywords:
-
- Incompressible Flow;
- Open Channel Flow;
- Turbulent Flow;
- Vortices;
- Boundary Conditions;
- Low Reynolds Number;
- Navier-Stokes Equation;
- Three Dimensional Flow;
- Fluid Mechanics and Heat Transfer