A DIAGNOSTIC STUDY OF TURBULENCE FEATURES IN WIND-TUNNEL FLOW OVER SIMPLE TOPOGRAPHIC SHAPES

The turbulence features observed in wind tunnel experiments of flow ov er isolated simple-shaped two-dimensional hills and valleys are analys ed in the light of transport equations of Reynolds stresses in the str eamline coordinate system. The analysis has shown that near the surfac e the streamwise pressure gradient is the driving parameter for all th e stresses. At higher levels, the effects of streamline curvature and streamwise pressure gradient act differently on the source terms of st resses, showing that the shear stress is the most sensitive to streaml ine curvature, whereas the streamwise stress is the most sensitive to streamwise pressure gradient. Although two of the considered topograph ies are specular images, the turbulence response is not so, since it d epends on the sequence of curvatures to which it is subjected. The inf ormation and analysis presented mill constitute a valuable resource to those seeking an understanding of atmospheric boundary layer developm ent over complex terrain. It will also provide a support for the devel opment and validation of more rigorous turbulence models.