Within the NATO Research and Technology Organisation Applied Vehicle Technology (AVT)-161 task group, titled "Assessment of Stability and Control Predictions for NATO Air and Sea Vehicles," a 53° swept and twisted lambda wing with rounded leading edges is considered. In a first step, the symmetric flow conditions are analyzed in this paper in order to understand the corresponding flow physics. Experiments by the task group are used to develop proper numerical simulation tools for further applications in the design process of unmanned combat aerial vehicles as a part of future air-combat systems. The philosophy of the configuration under consideration is explained. The vortical flowfield is simulated using the DLR, German Aerospace Center TAU-Code applied with different turbulence models on various computational grids. Finally, a best practice is evaluated for medium and large angles of attack. A combination of these numerical results and experimental data lead to a proper understanding of the complex flow structure. Furthermore, this paper addresses the necessity for the predictability and understanding of controlled and uncontrolled flow separation, together with the interaction of the corresponding vortex systems in order to estimate stability and control issues for the entire flight envelope. NomenclatureA = attachment line C¿ = lift coefficient; ¿/(^oo • S) Cl = rolling moment coefficient; l/(q^ • S • c^f) Clß = rolling moment due to sideslip; 9C,/9Ĉ " = pitching moment coefficient (noseup positive); c" = yawing moment coefficient; «/(í/^, • 5-Cref) c"ß = yawing moment due to sideslip; 9C"/9Ĉ p = pressure coefficient; {p -/'oo)/9oo Cf = root chord length of the model cVef = reference length / = frequency /j = moment of inertia around x I y = moment of inertia around y k = reduced frequency; 27r • / • c,^f/VM = Mach number 9tx) = dynamic pressure coefficient; p^ • V^/2 R = Reynolds number; V^ • c^f/v S = reference area 5 = separation line s = half-span Presented a.s

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SUMMARYThis paper presents a new approach towards the parallel local remeshing of unstructured tetrahedral grids on distributed memory parallel computers based on the message passing paradigm (MPI). The overall remeshing approach consisting of the parallel determination of the regions to be remeshed and the parallel local surface and volume remeshing is described in detail. An application of the remeshing algorithms in a time-accurate simulation of bodies in relative motion demonstrates the capabilities of the approach.

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The dynamic derivatives are widely used in linear aerodynamic models in order to determine the flying qualities of an aircraft: the ability to predict them reliably, quickly and sufficiently early in the design process is vital in order to avoid late and costly component redesigns. This paper describes experimental and computational research dealing with the determination of dynamic derivatives carried out within the FP6 European project SimSAC. Numerical and experimental results are compared for two aircraft configurations: a generic civil transport aircraft, wing-fuselage-tail configuration called the DLR-F12 and a generic Transonic CRuiser (TCR), which is a canard configuration. Static and dynamic wind tunnel tests have been carried out for both configurations and are briefly described within this paper. The data generated for both the DLR-F12 and TCR configurations includes force and pressure coefficients obtained during small amplitude pitch, roll and yaw oscillations whilst the data for the TCR configuration also includes large amplitude oscillations, in order to investigate the dynamic effects on nonlinear aerodynamic characteristics. In addition, dynamic derivatives havebeen determined for both configurations with a large panel of tools, from linear aerodynamic (Vortex Lattice Methods) to CFD (unsteady Reynolds-Averaged Navier-Stokes solvers). This work confirms that an increase in fidelity level enables the dynamic derivatives to be calculated more accurately. Linear aerodynamics (VLM) tools are shown to give satisfactory results but are very sensitive to the geometry/mesh input data. Although all the quasi-steady CFD approaches give comparable results (robustness) for steady dynamic derivatives, they do not allow the prediction of unsteady components for the dynamic derivatives (angular derivatives w.r.t. time): this can be done with either a fully unsteady approach (with a time-marching scheme) or with Frequency Domain solvers, both of which provide comparable results for the DLR-F12 test case. As far as the canard configuration is concerned; strong limitations for the linear aerodynamic tools are observed. A key aspect of this work are the acceleration techniques developed for CFD methods, which allow the computational time to be dramatically reduced while providing comparable results.