Investigate of Effect of Cylinder Roughness on Maximum Velocity of Density Current Body

Sedimentationin the dam reservoirs reduces storage volume sand as a result the useful life of the dam reduced.In deep dam reservoir the turbidity current usually are the reason of transport and deposition of sediment. If turbidity current completely stopped in middle regions of reservoir or not to allow deposition in sensitive areas, sediment deposition will decreased near dam wall and the main tasks of the dam will not be disrupt. Roughen the bed is a technique for changing the turbidity current hydraulic or slow it.Therefor in present research has been investigated the body velocity distribution of the density current on the bed with cylinder roughness and has been provided a relation for maximum velocity of body. A series of gravity currents experiment were performed into 35 cm width flume with 9 m length. The experiments developed as salinity fluid flow with 3 concentrations of 10, 15 and 20 lit/s in slop bed renge of 0.5, 1.25 and 2% and 3 roughness height of 25, 40 and 55 mm. The result indicates that the bed slope is in direct relationship with body velocity. Increasing the bed slop causes the maximum body velocity is closer the bed. And increases Roughness height reduces body velocity to certain extent.