Solid Brick Analogy For Automatic Grid Deformation For Fluid-Structure Interaction

Modern aerospace vehicles that operate at high angles of attack and perform aggressive maneuvers are subject to several dynamic loads problems such as buffet and flutter. Accurate model-based simulation of these problems requires careful attention to fluid-grid movement because it directly affects the energy transformation between the fluid and structure modes. A novel structural-based “solid brick analogy” for dynamic grid movement and remeshing for unsteady computational aeroelasticity is presented. The methodology is applicable to all types of structured and unstructured grids. In the solid brick analogy, the structural Navier equation is applied to the deforming portion of the CFD mesh, and solved by finite element or modal analysis. To preserve the grid smoothness and orthogonality, the nonlinear, large deformation with small strain rate theory is used. The geometrically nonlinear “brick analogy” can sustain shear deformation since the equilibrium is set up for a solid element instead of truss. The efficacy of the methodology is demonstrated and assessed for CFD grid movement of several aeroelastic problems. In addition, a high-fidelity multidisciplinary unsteady simulation of vertical tail buffeting of fighter aircraft model is presented. The results indicate the ability of the methodology to preserve grid quality, sustain shear, and reduce grid distortion.