EFFICIENT SIMULATION OF INCOMPRESSIBLE VISCOUS-FLOW OVER SINGLE AND MULTIELEMENT AIRFOILS

The incompressible, viscous, turbulent flow over single and multieleme nt airfoils is numerically simulated in an efficient manner by solving the incompressible Navier-Stokes equations. The solution algorithm us es the method of pseudocompressibility with an upwind-differencing sch eme for the convective fluxes, and an implicit line-relaxation scheme. The motivation for this work includes interest in studying high-lift takeoff and landing configurations of various aircraft. In particular, accurate computation of lift and drag at various angles of attack up to stall is desired. Two different turbulence models are tested in com puting the flow over a NACA 4412 airfoil; an accurate prediction of st all is obtained. The approach used for multielement airfoils involves the use of multiple zones of structured grids fitted to each element. Two different approaches are compared: 1) a patched system of grids, a nd 2) an overlaid Chimera system of grids. Computational results are p resented for two-element, three-element, and four-element airfoil conf igurations. Generally, good agreement with experimental surface pressu re coefficients is seen. The code converges in less than 200 iteration s, requiring on the order of 1 min of CPU time on a CRAY YMP per eleme nt in the airfoil configuration.