effect of urban geometric condition on Drag force coefficient of urban surface

Drag force coefficient (Cd) of various types of urban-like roughness was measured in a wind tunnel. The geometry of roughness used for measurement was determined to clarify the effects of arrangement pattern, packing density and variation of roughness height. The result indicates that the nonuniformity of roughness height increases not only Cd but also roughness length z0. This tendency is more obvious under the condition of high packing density