![]() ![]() Aircraft designers have created a variety of wings with different aerodynamic properties. Similarly, the displacements are computed on the undeflected FE model and coupled to the deflected CFD grid by maintaining the direction of the displacement vectors.Aircraft wings are airfoils that create lift when moved rapidly through the air. The forces are evaluated on the deflected flaps of the CFD grid and then transferred to the undeflected CSM grid by maintaining the direction of the force vectors, see Fig. For the transfer of forces and displacements, the deflection of control surfaces is only considered for the CFD grid, while the CSM flaps are undeflected. To reduce the computational effort for subsequent coupling cycles, the point-element-relationships are stored in registers. The point-element-relationships are initialized with the CFD and CSM grid in their undeflected flap configuration during the first coupling exchange cycle. The point-element relationships are computed by a nearest neighbour search, which is based on finding the nearest CSM element for each CFD node. The interpolation method is based on the point-element-relationship between the CFD- and the CSM-surface grid and has been validated with the BACT and HIRENASD test case. Thus, a new coupling algorithm has been developed for transferring forces and displacements between the surface nodes of the CFD-grid and the surface nodes of the structural finite-element (FE) model. The existing coupling algorithms in SimServer did not fulfill this requirement, especially as problems arose in combination with intersecting geometries, that can occur in combination with Chimera. 2.2 Fluid-structure couplingįor the computation of weakly coupled aeroelastic simulations with movable control surfaces, an important requirement to the fluid-structure coupling is the compatibility with the Chimera implementation. The RANS equations are closed with the Spalart–Allmaras one-equation turbulence model in the Edward’s modified version with rotational correction. For the spatial discretization, a finite-volume formulation with second-order upwind scheme is applied. In addition, convergence acceleration is achieved with the multigrid technique, for which a 3w cycle is utilized, using point-implicit relaxation. The inner iterations are reset to \(i=50\) after each flap rotation. After reaching the convergence criterion, the specified time steps for each deflection angle are completed but continued with the reduced inner iterations, so that a reduction in computational effort can be achieved. Aerodynamic and aeroelastic simulations at high dynamic pressure \(q=45\) kPa and transonic speed \(| < 0.001\) within the last 500 iterations. Numerical simulations with the flexible Chimera method are performed for the Model53 wing configuration, which is a generic delta wing with a deployed slat as well as an inboard and outboard trailing edge flap. The Chimera implementation of SimServer, suited for hybrid grids, is applied to model the control surfaces. Structural displacements are computed with a modal solver. In SimServer, the DLR-TAU Code is utilized to obtain the CFD solution by solving the Reynolds-Averaged Navier–Stokes (RANS) equations. The solution is based on coupled Computational Fluid Dynamics (CFD) and Computational Structural Mechanics (CSM) simulations embedded in the multidisciplinary simulation environment SimServer. A numerical tool for the computation of aircraft control surface aerodynamics with flexibility effects is presented.
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