Calculation of flow and pollutant dispersion in meandering channels

A mathematical model which takes full account of the three-dimensionality of the flow and pollutant concentration fields is presented. It is based on the solution of the momentum equations governing the flow, in the lateral, vertical, and longitudinal directions with a 3D numerical procedure along with the continuity equation. The turbulent stresses appearing in the momentum equations are calculated with a version of k-epsilon turbulence model that accounts for streamline curvature effects on turbulence. The pollutant concentration field is obtained from a solution to its transport equation. The model is tested by application to three different meanders for which velocity and concentration measurements are available, with channel width-to-depth ratios in the range 4 to 20, smooth and rough beds, and various pollutant-discharge locations. Comparisons of the velocity and concentration fields show good agreement.