Experimental Investigation of Gravity Current Frontal Velocity on Rough Beds

The frontal of gravity current is most important section of these flowtypes. The advance force in front is pressure gradient due to density differences between front flow and ambient fluid. In order to find the roughness effects as a resistor on frontal velocity, a series experiment of saline gravity currents were performed on rough beds with size of 0, 4, 7.5, 12 and 15 (mm). The saline gravity current with three inflow discharges of 0.7, 1 and 1.3 (lit/s) and three concentrations of 10, 16, 20 (g/lit)was flowed on slope beds from 0.05 to 2.2 steep percentage. For estimation of frontal velocity and assessing effects of parameters, a linear model by correlation coefficient of 0.9 and RMSE of 0.037 and mean ratio deficit of less than 10% was derived. By applying of linear modeling and linear standardization data, the efficiency index of slop, relative roughness and non-dimensional discharge (Richardson number) on prediction of non-dimension frontal velocity was estimated as 0.17,-0.50 and -0.35.