DRAG AND LIFT ON RECTANGULAR BLUFF-BODIES IMMERSED IN DEEP BOUNDARY-LAYER FLOW OVER ROUGH SURFACES

Measurements of drag and lift on three-dimensional rectangular bodies immersed in deep turbulent boundary layer flow over rough surfaces have been carried out in a boundary layer wind tunnel. The experiments described in this paper deal with the effects of building geometry, shear flow characteristics and angle of attack of approaching flow on wind load. A significant influence of building geometry was found. Furthermore, drag coefficients measured in boundary layers flows over two differently rough surfaces show differences up to 25%. For zero degree angle of attack the drag coefficient based on the shear velocity u* is a function of the ratio of building height H to roughness length zo and building geometry. However, the use of u* and zo as scaling parameters results in a power law expression with exponents and factors showing additional dependences on flow conditions and building geometry. © 1990.