The flow dynamics in Grimsbury reservoir is studied using Computational Fluid Dynamics (CFD). Under no wind condition, flows circulate in the horizontal plane. These circulations, in general, lead to short circuiting and zones of stagnation. Modifications to the inlet and the outlet are investigated to maximise the residence time. They include the manifold inlet arrangement, the submerged baffle inlet and the central outlet arrangement.
The results of the residence time simulation indicate that the manifold inlet option gives the best ‘plug-flow’ efficiency, next the submerged baffle option and finally the central outlet option. The submerged baffle inlet option, however, is considered to be the preferred option because of its low installation cost and because of the reasonable balance between the degree of mixing and the residence time.