Evaluation of mixing capability improvement of a circular water storage tank by nozzle system retrofit using computational fluid dynamics

Studies on the mixing of water storage tanks typically consider vertically oriented nozzles, however, not much consideration was given for horizontally oriented nozzles. This paper aims to employ computational fluid dynamics (CFD) to study the influence of horizontal nozzle configurations on the mixing within a typical circular water storage tank. The impact of the outlet locations and water depths on mixing time was also investigated. The results from the numerical simulations show that nozzle configuration with horizontal distance between the sets of nozzles of 0.71 tank diameters apart performed the best. An outlet located in the center of the circular storage tank encourages near-floor lateral movement of fluid and improved the velocity uniformity across the water column. The water depth was found to have a non-monotonic relationship with the mixing time and the depth to diameter ratio of 0.4 provides the best mixing in the studied tank with nozzles.