Sediment transport in ice-covered channel under non-equilibrium condition

Many rivers and lakes located at high altitudes in different parts of the world experience ice conditions during the winter for prolonged period and an ice cover on the top causes a transition from an open flow state to a closed underflow one. The distribution of the suspended sediment concentration is presented under such condition where the concentration is a function of spatial coordinates along with time. Existing expressions of eddy viscosity and settling velocity are used that contain the combined effects of both the lower channel bed and the upper ice cover boundary. The flow is considered sediment free initially and assumes a uniform inlet condition. No mass transfer is taken on the ice cover surface and a constant reference concentration is assumed at the reference level. Numerical method (ADI method) has been utilized for the solution of the PDE in conjunction with the given initial and boundary conditions. It is found that with increasing time and downstream distance, concentration values first increase along a vertical and then reach a stable value. Following this, the solution is compared with the available experimental data at large time under far-field conditions. At the end, the concentration profiles are analysed by varying different parameters. It is seen that as the dimensionless correction coefficient present in the settling velocity expression increases, the concentration values also increase. An opposite result is found when the dimensionless proportionality constant present in the eddy viscosity expression is varied and in comparison to lower times, the amount of concentration change occurs rapidly with higher times.