THE EFFECT OF BED ROUGHNESS ON ENERGY LOSS IN OPEN CHANNEL FLOWS

Open channel flow is defined as fluid flow with a free surface open to the atmosphere. One of the main sources of resistance in open channel flow is the roughness of channel bed. The roughness of channel base and side walls must be considered seperately investigating the the bed roughness. A series of experiments were carried out under laboratory conditions to examine base and side wall roughness. Roughness coefficient in open channel flow is usually represented by Manning coefficient. In this study a series of experiments were performed to calculate the Manning coefficients of different roughness elements in order to observe the effect of roughness forces on energy loss. Experiments are conducted in a rectangular laboratory channel in steady flow conditions. Different water depths were used at the same flowrates. Rougness elements were anchored to the base of the channel, side walls of the channel and both base and side walls of the channel in order to observe the side wall effect.