Development and improvement of two methods of different complexity to simulate atmospheric boundary layer turbulence for aircraft design studies

In this paper we present two different methods to provide turbulence data for aircraft design studies. The first method is based on the discrete gust approach which describes one single gust event as analytical approximation. Based on mean gust shape calculations in turbulent wind fields obtained from high-resolution largeeddy simulations (LES), we suggest both a new one- and two-dimensional gust shape model. The one-dimensional gust shapes differ significantly from the classical one-minus-cosine gust. Two-dimensional mean gust shapes show elliptically shaped contours with varying aspect ratios for different gust diameters. The second and more complex method provides three-dimensional turbulent wind speed data from LES. This approach allows to consider explicitly the influence of buildings on aircraft during take off or landing. In order to quantify the influence of an idealized airport building on aircraft, a virtual crosswind landing trough the wake of a building was simulated within the LES data. Following the 7-knots-criterion, the building induced flow disturbances may have a significant influence on landing aircraft. Both methods will be used in future to initialize a computational fluid dynamics (CFD) model to simulate the flow around an aircraft.