Numerical modelling of dispersion of suspended particles in a turbulent open channel flow: A fitted operator approach

In this article, a mathematical model based on convection-diffusion equation with the Dirichlet boundary conditions has been simulated to study the process of longitudinal spreading of the particles with suspension and settling velocity into turbulent shear flows over a uneven bottom surface. The tracers are discharging from a continual elevated point-source. The computed solution exhibits adumbration of settling of particles as the equi-concentration contour plots. At the free surface, the eddy diffusivity tends to zero. Consequently, the convection-diffusion problem becomes convection dominated. Typically, the result for these type of models demonstrate sharp layer phenomenon which demands for a special numerical treatment. Conventional numerical methods fail to produce acceptable computational results on a uniform mesh. The numerical scheme considered here is based on two-dimensional fitted operator on a uniform mesh. The scheme successfully captures the layer phenomenon depicted by suspended particles at various locations. The numerical results are in good agreement with the experimental data available in the previous literature.