DIFFICULTIES IN PREDICTING VORTEX BREAKDOWN EFFECTS ON A ROLLING DELTA-WING

An analysis has been performed of the challenges encountered when tryi ng to predict the unsteady aerodynamics associated with the breakdown of the leading-edge vortices on a 65-deg sharp-edged delta wing, descr ibing roll oscillations around an axis inclined 30 deg to the freestre am, It is shown that to produce a realistic prediction the mathematica l model has to represent in a satisfactory manner the highly nonlinear , almost discontinuous steady and unsteady aerodynamic characteristics associated with the downstream travel of the vortex breakdown past th e trailing edge on the leeside wing half at 5 < \phi\ < 8 deg.