A three-dimensional Euler aerodynamic method based on a finite-volume, multistage time-stepping algorithm is used to simulate free vortices generated by flow separation along the edges of swept, slender wings at moderate to high angles of attack. Computed results for a cropped-delta wing, an arrow wing, and a strake-wing-body configuration are correlated with experimental data and, for cropped-delta wing, with predictions of other numerical methods also. The flow is impulsively started and the vortices are automatically captured. The following two issues are specifically addressed: 1) sensitivity of the solutions to artificial viscosity and 2) effect of grid density on the results. Relatively small changes in the subsonic solutions are noticed with variations in the magnitude of artificial viscosity parameters and grid density. The correlations presented here provide an added measure of confidence in computational simulations using the Euler equations. The present investigation also raises some new issues related to vortex instabilities.
Flow in a deep turbulent boundary-layer above a rough, rigid, wavy surface is considered. Closure is made via mixing-length hypotheses and at the level of the turbulent energy equation and the resulting equations are solved numerically using finite difference approximations. Results are presented for a typical case representative of flow above gravel waves on the bed of a tidal channel and the effect of changes in wave amplitude, shape and surface roughness are considered. Comparisons are made with recent experimental and theoretical studies. In some computations allowance is made for the effect of streamline curvature on the turbulence structure and the importance of such effects for these flows is assessed.
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