FINITE ELEMENT ANALYSIS OF FLOWS IN SECONDARY SETTLING TANKS

The hydrodynamics in settling tanks of wastewater treatment plants are characterised by a dispersed fluid-solid flow. The behaviour of water and suspended solids is strongly coupled, and this coupling leads to complex flows. With the aid of Computational Fluid Dynamics techniques a more detailed and comprehensive understanding of this effect can be obtained. In this work the finite element method is used to simulate the fluid-solid flow in a settling tank. An explicit Eulerian velocity correction scheme has been deployed to solve the Navier-Stokes equations. The Streamline Upwind / Petrov-Galerkin method is applied in order to avoid numerical instabilities due to convection. 1