The Use of Log -Wake Law and Turbulent Equation to Describe Flow Behavior in Steep Slope Stream

Abstract

The log-wake law for turbulent current has been developed. And tested with laboratory data based on turbulent flow in smooth pipes. For this paper, the equation has been developed for use in stepped spillway. Where the log-wake law can be divided into three parts. First part, the logarithmic equation, which describes the effect of shear stress between the flow layers. Assumes von Karman constant is 0.41. The second part, the third-degree polynomial equation, describes the effect of shear stress on a wall. And the last part, the fourth-degree polynomial equation, which describes the effect of changing the flow pressure brush, which is like to the wall-free shear stress. The Coles wake law with a constant wake strength about 0.126. The test used 68 data sets, the flow rate between 0.0233-3.285 m³/s, the flow slope between 14-30 degrees, and the step height between 0.0380-0.610 m. It was found that the developed log-wake law could better characterize the flow in stepped spillway than the turbulent flow log-wake law in smooth pipes. Making it known that the precision of the log-wake law has nothing to do with degrees of stepped spillway or flow rate. But will depend on the height of the steps.