AWWA QTC98275

Thames Water has over 200 treated water reservoirs within its operational area. These reservoirs, found at various locations in the distribution network, are used to maintain the water pressure downstream and to act as storage for emergencies. There has been concern that poor mixing within these structures may contribute to water quality deterioration. This paper discusses the computational fluid dynamics (CFD) tool to analyze the flow dynamics in the reservoir and to study the reservoir mixing. Various parametric models have been proposed to model the mixing. They represent the reservoir either as a series of complete mixed tanks or as a number of interacting zones. However, it is difficult to find a parametric model that would fit to a class of reservoirs and so the parameters used by the model must be determined individually for each reservoir. The results in this work are obtained using the commercial CFD Fluent code. Two CFD methods, the Volume of Fluid (VOF) and the deforming mess (DM) can be applied. The VOF method is a multiphase method and is used to simulate single velocity field applying for both air and water. The water surface is modelled explicitly using the air/water volume fraction. The DM method models the water phase only, the variation of water level is modelled as the moving flat wall boundary. The DM method is preferred because of the significant improvement of the computation time. The DM method is used in subsequent simulations to discuss the reservoir mixing performance. Comparison between the two methods is performed to check for the validity of the assumptions in the DM method.

Product Details

Published:

01/01/1998

ISBN(s):

0898679796

Number of Pages:

12

File Size:

1 file , 240 KB