Improvements in mixing operations of water treatment plants by use of a stable finite element model.

This work shows improvements made in mixing operations at water treatment plants, as a result of the hydrodynamic analysis of the mixing processes carried out by the use of a Finite Element Model. The code, developed in the Civil Engineering Department of the University of La Coru?a, Spain, solves the Navier-Stokes equations that rule viscous incompressible flow by using a Streamline Upwind/Petrov-Galerkin (SUPG) stabilization technique. The incorporation of the SUPG formulation leads to obtaining stable solutions for Reynolds numbers of a moderate order in connection with meshes that are not very refined. Some water treatment units present significant deficiencies in their design. The numerical evaluation of the flow avoids the high expenses of the trial-and-error processes involved in installing and removing the mixing mechanisms and those derived from the need to halt the water treatment processes. As a result, an optimum design of the treatment plant is obtained at a low cost.