Stern Boundary Layer Flow On A Three Dimensional Body Of 2 1 Elliptic Cross Section

Stern Boundary-layer Flow on a Three-dimensional Body of 2:1 Elliptic Cross Section

A comprehensive set of experimental data for flow over the stern of a three-dimensional model having 2:1 elliptic transverse cross sections, suitable for analytical comparisons, is presented. Included in this set are surface pressure and shear stress distributions, static pressure and mean velocity profiles, and Reynolds stresses. The eddy viscosity and mixing length values obtained from the measured Reynolds stresses and mean velocity gradients are also presented. The measured and derived data are compared with the predictions of existing three-dimensional theoretical methods. These comparisons confirm the need for improved prediction techniques in the thick turbulent boundary-layer region of the stern. (Author).

Curvature Effects of Three-dimensional Thick Stern Boundary Layers

Thick boundary-layer equations, including the variation of the metric coefficients with distance normal to the surface, are solved from the nose to the tail of an elongated three-dimensional body. Iteration between potential and boundary-layer flow solutions is adopted to obtain a converged solution in the stern region. The complete procedure makes use of Keller's box numerical scheme in a non-orthogonal curvilinear coordinate system and an isotropic eddy-viscosity model for the Reynolds stress tensor in both streamwise and crosswise directions. The numerical method allows the calculation of flows in which the crosswise component of velocity cntains regions of flow reversal across the boundary layer. The inviscid pressure is determined by using the Hess-Smith method. The program is validated for an axisymmetric body, and then the calculations are compared with measurements for two three-dimensional bodies having elliptical transverse sections. Keywords: Thick turbulent stern flows; Longitudinal and transverse curvature effects; Turbulence modeling; and Eddy viscosity.

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