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The results are compared to predictions using the boundary condition originally devised by Wilcox [11] for rough surfaces, and to predictions with the Spalart-Allmaras model with the Boeing roughness extension by Aupoix and Spalart (ASB) [2]. Good agreement with experiments has been achieved with respect to the influence of the roughness on the velocity profile, the skin friction coefficient and the loss in lift. 1 Introduction The influence of wall roughness on the characteristics of turbulent flow is of technical interest in the field of aircraft icing or turbine blade erosion.

This data, which needs to be determined for every possible flight condition, is used to design the structure of the aircraft and the flight control system. Currently, this data is obtained mainly from costly wind tunnel tests or using hand-book methods. The use of higher-fidelity and thus more time consuming CFD methods has been, up to now, impossible due to the large volume of data required. The long-term goal of the work described here is the development of a process chain for the efficient numerical prediction of all relevant aerodynamic data for the elastic aircraft over the entire flight envelope, based on a hierarchy of CFD methods of increasing fidelity.

27–34. V. Fischer and W. Polifke ∂τ where ω˙ is the filtered reaction rate of the cell and ∂xiφi denotes the subgrid–scale scalar stress, which can be modelled, for example, by using an eddy–diffusivity– approach as suggested by [4]. e. filtered) values are taken into account for the mixing state. 2 Motivation The mixing state itself can be represented by Filtered Density Functions (FDFs). Several alternatives have been suggested to represent such FDFs: 1. In order to minimize computational effort, functions of presumed shape can be employed.