Water quality and mixing models for tanks and reservoirs

Abstract

Using three types of models, researchers studied mixing and water quality in an aboveground cylindrical reservoir. Long detention times and improper mixing in tanks and reservoirs may negatively affect water quality. Mathematical and physical models of mixing and water quality dynamics may be used to determine how alternative designs or operational policies affect the quality of water within and leaving the facility. Three models—a systems model that uses a simplified representation of the reservoir emphasizing the input and output from the facility, a computational fluid dynamics model based on mathematical equations, and physical scale models of the reservoir—were applied to the Ed Heck Reservoir, a 4‐mil‐gal (0.015 X 106 m3) cylindrical reservoir in Azusa, Calif. Results of the application of each model are presented graphically along with a discussion of each model's advantages, disadvantages, and costs.

Effects of water inlet configuration in a service reservoir applying CFD modelling

“…Field experimental studies and modelling are the two basic tools used for research in hydraulic and drinking water quality issues in storage tanks. Grayman et al (1996) compared the results of the physical modelling, systems modelling and CFD with experimental data, obtained from a tracer test in a cylindrical tank with simultaneous water inlet and outlet. They found suitable agreement between field data and modelled results.…”

“…These authors also simulated a tracer test for 33.5 hours and found higher concentrations in the external ring of the tank compared with experimental measurements and also a non-symmetric pattern in its cross section which was not recognized experimentally due to limited sampling points. Additionally, the experimental work identified a significant increase of the tracer in the upper region of the centre of the tank which was not observed in the modelling, likely due to non-consideration of the thermal effects over the flow pattern (Grayman et al, 1996). Van der Walt (2002) research included CFD simulations of diverse scenarios about free residual chlorine decay in a storage tank.…”

Nouvelle approche pour déterminer la distribution des temps de séjour dans les réservoirs d'eau potable en régime non permanent

“…De nombreuses études ont porté sur la modélisation de la qualité de l'eau dans les réservoirs d'eau potable à l'échelle pilote (Grayman et Clark 1993;Woodward et al 1998;Rossman et Grayman 1999;Grayman 2000) ou à l'aide de simulations numériques Grayman et al 1996;Hannoun et al 1998;Ta 1998;Wang et Falconer 1998a, 1998bGrayman 2000). Toutes ces études ont montré que le temps de séjour est une variable déterminante pour la qualité de l'eau.…”

Numerical simulation of the hydrodynamics and turbulent mixing process in a drinking water storage tank

“…However, only a few CFD studies have approached the modelling of turbulent flow in drinking water storage tanks (Grayman et al, 1996;Hannoun and Boulos, 1997;Martínez-Solano, Mora-Rodríguez, Iglesias-Rey and López-Patiño, 2010;Palau-Salvador et al, 2007). This paper presents the results of three-dimensional simulations of the flow and jet mixing in a jet-agitated drinking water storage tank with constant level.…”