Validation of the Computational ANSYS -CFX code for Free Surface Flow: Skimming Flow over Non-Uniform Step Size Stepped Spillways

Abstract

A B S T R A C T:Stepped cascades have obtained much attentiveness by engineers in hydraulic field from multiple sides as its high production in losing energy and simplicity of construction, mostly after spreading of RCC in the building technology. The flow above stepped cascade can be classified into three various flow cases: Nappe flow, transition flow, and skimming flow conditions. The aim of current study is to calibrate computational (ANSYS-CFX) code by accessible data of experiment. The calibration is managed to compare the computational and laboratory results with respect to the location of free water surface and velocity distributions for flow discharges in skimming condition. In the investigation three grid particles 0.012, 0.015 and 0.018m are tested in order to optimize both the perfection of the results and the running time. Also, the Volume of Fluid (VOF) multiphase model is adopted to observe the behavior of mixed flow over the cascade chute. Further, the turbulence model of Renormalized group of k-ɛ (RNG) is applied to determine the effects of mixing flow structure on the flow velocity above that step formation. Additionally, the inlet and outlet boundary technique is utilized to carry out the flow condition in steady state. The results of the current work are promising and inspired great confidence between computational outcomes and laboratory metered data.