Fundamental Issues in the Calculation of Rotor Wakes

The role of vortex structure and stability in the calculation of acoustic and aerodynamic features of rotor wakes will be discussed. Results of vortex panel calculations of the roll-up of an axisymmetric vortex sheet will be presented. The use of rediscretization to supress small-scale instabilities will be considered. Calculations of the growth of three-dimensional perturbations during the roll-up of axisymmetric vortex sheets will also be presented.