On the Difference between Developments of Two- and Three-Dimensional Turbulent Boundary Layers

Abstract

Computational investigation was made on characteristics of incompressible turbulent boundary layers on a shiplike body and on two kinds of two-dimensional bodies. One of the latter bodies had nearly the same contour as one of the Streamlines on the three-dimensional body. The other had pressure distribution on it the same as along the streamline on the three-dimensional body. Momentum thickness, shape parameter and surface cross-flow angle of the boundary layer were calculated for the three cases and factors contributing to variations of these quantities were analyzed. Comparison between the results for the three cases revealed the following facts. The rate of growth of the momentum thickness in the region of deceleration was promoted mainly by the streamline convergence which was absent in two dimensions. In this case the development of the momentum thickness became larger in the three-dimensional boundary layer than in the two dimension alone. The surface cross-flow angle near the rear stagnation deviated rapidly in the direction of the center of streamline curvature due to the curvature and convergence of the three-dimensional streamline.