Experimental and modelling study of flow characteristics on large-scale roughness bed

Abstract

Large-scale roughness bed flow is a special flow condition which is commonly seen in mountainous rivers. In this paper, gradient flume experiment is carried out with plum-blossom distributed cubic obstruction blocks with 50 mm edge, and large-scale roughness bed flow characteristics including free surface morphology, flow velocity distribution, turbulence propagation and friction head loss coefficient are studied by high-precision measuring and statistical analysis. In addition, CFD based numerical model is established in this paper to verify the experimental results and provide a prediction method to expand the experiment. After that, a modified empirical formula of friction head loss coefficient considering more important influence factors is proposed in this paper based on the experimental results and the numerical simulation results, which provide a practical calculation method of friction head loss coefficient for engineering reference.