NUMERICAL INVESTIGATION OF AN INTERNAL LAYER IN TURBULENT FLOW OVER A CURVED HILL

The development of an internal layer in a turbulent boundary layer flow over a curved hill is investigated numerically. The turbulent flow equations are solved by a control volume based, finite-difference method. The turbulence is described by a multiple-time-scale turbulence model. Computational results show that the internal layer is a strong turbulence field that develops beneath the external boundary layer and is located very close to the wall. The turbulence field of the boundary layer flow over the curved kill is compared with that of a turbulent flow over a symmetric airfoil (which has the same geometry as the curved hill except that the leading and trailing edge plates were removed) to study the influence of a strongly curved surface on the turbulence field. The turbulence structure in the near-wall region of the curved hill is almost the same as that of the airfoil in most of the curved region even though the approaching external flows are quite different. Results show that the development of the wall shearing stress and separation of the boundary layer at the rear of the curved hill depend mostly on the streamline curvature and are only slightly influenced by the external boundary layer flow.