Numerical Analysis of Flow in Sedimentation Basins

The equations governing two-dimensional, steady flow in circular and rectangular primary settling basins are formulated. Mean-flow equations expressing conservation of mass and momentum are combined with a two-equation turbulence model (k-ϵ model) to compute velocity fields in sedimentation basins. The turbulence is characterized by a turbulent kinematic eddy viscosity which is computed directly as part of the solution. A numerical solution to the mathematical model is formulated by application of the Galerkin finite element method to the equation residuals. The resulting non-linear system of equations is solved by a variation of Newton's method. The model is applied to predict the flow pattern in a rectangular settling basin. A vector plot of the basin velocity field and contour plot of the turbulent kinematic eddy viscosity are presented.