Comparison of different approaches for modeling atmospheric effects like gusuts and wake-vortices in the CFD code TAU

Abstract

Two different methods for modeling of atmospheric effects have been implemented into the CFD code TAU. The first one is the so called disturbance velocity approach, a simplified method which allows predicting the influence of gusts or wake vortices on the aircraft, but not vice versa. Alternatively, an unsteady boundary condition has been implemented to feed in the atmospheric disturbances into the flow field. Thereby the mutual interaction of atmospheric disturbances and aircraft is captured. Both methods are compared for 3D applications in order to access the validity range of the simplified approach. A result is that the simplified approach is sufficient accurate for scenarios relevant for the certification process of aircraft. Even for a gust wavelength down to one reference chord length the agreement of the highly accurate method and simplified approach is fair. To demonstrate the capability of the simplified method for industrial applications, the maneuver of a generic fighter configuration through the wake vortices of an aircraft in front is simulated. The reaction of the aircraft due to the additional loads has been taken into account by coupling of CFD with flight mechanics.