Abstract
Relationship between flow resistance and rough wall surface having semicircular ribs was investigated experimentally. Concentric cylinder device was employed to carry out the experiments. We measured flow resistance directly by the torque meter of the inner cylinder and velocity distribution by the LDV. In order to estimate the flow resistance over the wall surface having semicircular ribs, we focus on the interval of ribs. The approaching velocity to the next rib can be approximated by the measured velocity distribution and interval of ribs. Based on this approximation, we can estimate the approaching velocity without measurement of velocity distribution. Finally, we constructed the model for the prediction of flow resistance, and we estimated the pressure drag and frictional drag by this model. As a result, the estimated flow resistance has good agreement with the measured flow resistance.
