An algebraic grid motion technique for large deformations

Numerical simulation of the aeroelastic behaviour of wings and rotor blades requires the coupling of an unsteady flow-solver with a structural model. The moving and deforming surfaces resulting from unsteady simulations require deforming meshes during the simulation, and it is common practice to use simple interpolation of surface displacements and velocities onto the initial undisturbed mesh. However, such techniques result in poor grid quality, and possible grid crossover, when applied to large surface displacements or deformations. A new interpolation technique, for structured grids, is presented which is still simple in that it is driven solely by surface motion, but maintains grid quality near the surface by representing rotational effects there. Furthermore, since the scheme is fully analytic, the grid speeds required in an unsteady flow-solver are also available analytically, and the scheme is very cheap computationally.