Numerical Simulation of Water Tank Circulation and Water Age Under Different Working Conditions

Abstract

AbstractWith increasing real estate and apartment vacancy rates, the utilization rate of the water in water tanks is decreasing; this leads to an increase in the water age and deteriorates the water quality in water tanks. The general hydrostatic numerical model cannot simulate the flow field and water age of a water tank correctly because the horizontal scale of the water tank is equivalent to the vertical scale, and the vertical hydrostatic approximation assumption is no longer applicable. In this paper, the water age module is added to a three‐dimensional numerical model based on estuarine and coastal oceans, and a nonhydrostatic numerical model is developed to simulate and analyze the three‐dimensional flow field and the temporal and spatial variations in the water age of the water tank under different working conditions. The total water consumption and the effective volume of the water tank are the main factors affecting the water age, followed by the water level change range. The water age can be reduced to a lesser extent by setting the position of the inlet and outlet at a diagonal angle and adopting a larger inflow velocity. The distributions of the circulation and water age are mainly determined by the inlet in the influent process. There is no obvious dead water zone in the tank due to the strong disturbance, advection and diffusion in the secondary water supply process. The water age distribution in the water tank is mainly affected by advection, while diffusion plays a secondary role.