Antisymmetric boundary condition for small disturbance CFD

Abstract

The class of small disturbance CFD methods, also referred to as linearized CFD methods, is an efficient and accurate means for the prediction of unsteady aerodynamics. Small disturbance CFD methods are successfully used for the computation of generalized aerodynamic forces that can be directly utilized in aeroelastic analyses. Although small disturbance CFD does not achieve the performance of established linear-potential-theory-based methods in terms of computational efficiency and memory requirements, it provides superior fidelity for transonic flows and geometrically complex configurations. To further improve the applicability towards industrial investigations, a novel boundary condition for small disturbance CFD is introduced, which allows to exploit the properties of antisymmetry in the case of antisymmetric modal deflections. Thus, by means of the novel antisymmetric boundary condition all simulation cases without sideslip angle can be treated with a half-model of the configuration. The approach reduces both the required memory and the computational effort for small-disturbance-CFD-based simulations by a factor of approximately two. The antisymmetric boundary condition is successfully validated based on the AGARD 445.6 wing and the Common Research Model.