ON LIMITERS FOR MINIMAL VORTICITY DISSIPATION

Limiters that minimize the numerical dissipation of vorticity are considered. It is shown that for a typical vortex the velocity in the direction normal to the vorticity and the gradient of the absolute value of the vorticity reaches a maximum, switching on whatever limiter is being employed, and dissipating the vortex. Based on this insight a local change of coordinates is performed in order to limit differently the velocities in the characteristic directions of the vortical flow. This reduces the dissipation markedly. An example is included that compares the new limiter to existing ones, as well as to results using the usual vorticity confinement options. I