Eric Grohn
Abstract
The AguaClara project team develops a simple, low-cost water purification plant for developing global communities. One part of the AguaClara plant is a sedimentation tank. During this stage of the purification, large coagulated contaminant particles (”flocs”) collect and settle out of the water, leaving it cleaner than before. Recently, one problem has been noticed with the current design of the AguaClara sedimentation tank. If the water entering the tank is warmer than the water already within, the tank doesn’t perform as well as it should. The suspected reason for this is that the warm buoyant water rises rapidly to the top of the tank, taking the flocs with it, at a velocity that is too great for the tank to function correctly. The top of the tank consists of an array of angled closely packed parallel plates called plate settlers. My project here is to determine the flow pattern for a convective flow through the plate settlers, with the hope that this will provide a clearer picture of the poor sedimentation tank performance. A 2d analytical solution is determined for the flow velocity between two angled parallel plates when the flow is convective. Further topics are discussed as they relate the sedimentation tank performance, such as turbulence between opposing flows and shear flow instabilities.
