Modeling depth-averaged streamwise velocity in straight trapezoidal compound channels with ice cover

Abstract

This study considers the flow of water in ice-covered compound channels with straight trapezoidal cross-sections. For describing the lateral distribution of depth-averaged streamwise velocity in aforementioned channels, a modified analytical model, which incorporates the influences of channel bed friction, ice cover resistance, lateral shear turbulence and secondary currents, is derived by the Shiono and Knight method and a two-layer hypothesis. Then the analytical model is applied to straight compound channels with full ice cover and symmetrical shore ice. The modeled results of the two cases, which employ appropriate boundary conditions, indicate good predictions for the transverse distribution of depth-averaged streamwise velocity when compared with captured experimental results. Subsequently, the intensities and rotational directions of secondary flows and the dimensionless comprehensive eddy viscosity effect are exhaustively discussed, finding that the intensities of secondary flows in the main channel domain for the two cases present opposite changing laws as flow depth increases, and the signs of secondary flow coefficients are verified to be consistent with experimental observations. The theoretical approach used herein can supply some guidance for investigating the flow characteristics of ice-covered channels.