Numerical solutions of atmospheric flow over semielliptical simulated hills

In the present approach the partial differential equations for the vorticity, stream function, turbulence kinetic energy, and turbulence length scale are solved by a finite-difference technique. The numerical solutions have been compared with available experimental data; agreement is good.

It is found that the mechanism of flow separation induced by a semiellipse is the same as in the case of flow over a gradually sloping surface for which the flow separation is caused by the interaction between the viscous force, the pressure force, and the turbulence level. For flow over bluff bodies, e.g., solid fences, a large downstream recirculation bubble is created due to the inability of the flow to negotiate with the abrupt change of the surface shape. Increasing the aspect ratio and/or increasing the turbulence level results in flow reattachment close behind the obstacle.