Implicit/multigrid algorithms for incompressible turbulent flows on unstructured grids
William Kyle Anderson, Russ D. Rausch, Daryl L. Bonhaus · 1995
An implicit code for computing inviscid and viscous incompressible flows on unstructured grids is described.The foundation of the code is a backward Euler time discretization for which the linear system is approximately solved at each time step with either a point implicit method or a preconditioned Generalized Minimal Residual (GMRES) technique.For the GMRES calculations, several techniques are investigated for forming the matrix-vector product.Convergence acceleration is achieved through a multigrid scheme that uses non-nested coarse grids that are generated using a technique described in the present paper.Convergence characteristics are investigated and results are compared with an exact solution for the inviscid flow over a four-element airfoil.Viscous results, which are compared with experimental data, include the turbulent flow over a NACA 4412 airfoil, a three-element airfoil for which Mach number effects are investigated, and three-dimensional flow over a wing with a partial-span flap.