A numerical study of the unsteady motion of a wing using N-body approximation

Numerical simulation of unsteady motion of wing through undisturbed fluid is formulated using Unsteady Vortex Lattice Method. Singularities in the form of vortex ring elements are distributed over the surface of the wing mean camber and remain fixed in space. The wake vortex ring singularities are free to deform under the action of velocity field induced by the combination of moving wing and deforming wake vortex ring elements. CL, CDi, Г distribution etc., are calculated for different cases of unsteady motion. A free-wake algorithm is developed based on the higher order numerical integration schemes. Minimum cut-off distance to avoid r-1numerical singularity is obtained from Rankine vortex model. No-normal ow boundary condition is imposed over the surface of mean camber and the resulting MN × MN equations are solved for Г using LU decomposition.