AFFLUX DUE TO PIER GROUPS IN OPEN CHANNEL

Abstract

n investigation of flow past pier groups in open channel has been carried out experimentally for Froude number ranging from 0.19 to 0.387, Reynolds number ranging from 4.6 x 104 to 7.6 x 104. The objective of the present study was to compare the results for three interrelated problems, viz., drag, afflux and energy loss for OR-3 with that of equivalent solid circular cylinder and also with those of OR-1 and 2. In gradient flow problem, afflux and energy loss depend strongly on drag coefficient of obstruction. Dray coefficient for pier group has been obtained from experimental study and that for equivalent solid circular cylinder has been obtained ..t.heoretically by procedure suggested by Ranga Raju et.al. (to). The knowledge of drag coefficient enables the computation of afflux and energy loss using the theoretical equations. It has been observed that the average drag coefficient of OR-3 is clearly larger than that of OR-1 and somewhat less than that of equivalent solid circular cylinder. Since there is considerable scatter in the data of the present study, it has not been possible to compare OR=3 VItti OR,4, Pqrther, the values of afflux and energy loss for OR-3 are smaller than those of equivalent solid circular cylinder.