Experimental and numerical investigation of flow patterns in shallow rectangular reservoirs with symmetrically positioned inlet and outlet channels

Daniel Augusto De Miranda,Álefe Marques Dos Reis,Márcia Maria Lara Pinto Coelho

doi:10.1590/2318-0331.231820170125

Abstract

ABSTRACT Shallow flows correspond to turbulent flows whose horizontal dimensions are considerably larger than the vertical one. In Hydraulic Engineering, they refer, e.g., to stormwater basins, stabilization ponds for wastewater treatment and aquaculture tanks. Since they involve low flow velocities, a continuous settling process often affects such shallow reservoirs. Therefore, it is important to expand the knowledge about the influence of its geometry on the hydrodynamic behavior and the sedimentation tendency. This paper aims to analyze flow patterns in a rectangular reservoir with symmetrically positioned upstream and downstream channels, taking into account three different flow rates under steady flow regime (0.50, 1.25 and 3.40 L/s). Experimental tests were performed in a laboratory prototype, consisted of a 3.0 m long and 2.0 m wide reservoir, with a maximum depth of 0.30 m. Also, it was applied the WOLF 2D software for numerical modeling of all variants. Experimentally, a symmetrical hydrodynamic behavior was observed only for the lowest flow rate, while the flow pattern was asymmetrical for the other cases. On the other hand, the numerical model indicated hydrodynamic symmetry for all scenarios.

Highlights

Shallow flows are defined as layered turbulent flows bounded by a bottom surface and by another surface in contact with the atmosphere, characterized by horizontal hydraulic dimensions significantly greater than the vertical one (JIRKA; UIJTTEWAAL, 2004).The study of shallow flows involves a range of applications in Hydraulic Engineering domain and their respective areas of interest
It can be highlighted the study of hydrodynamics and morphodynamics of shallow reservoirs, such as: (1) detention basins, often employed in urban drainage projects for flood control (PERSSON; WITTGREN, 2003; JANSONS; LAW, 2007); (2) stabilization ponds of sewage systems, whose sedimentation efficiency must be high so that they have adequate performance (OLUKANNI; DUCOSTE, 2011; CAMNASIO, 2012; LI et al, 2013); (3) aquaculture tanks, which demand a correct understanding of their hydraulic behavior, since they are associated with the development of fish, algae and crustacean cultures (MASALÓ, 2008); as well as many other water storage systems susceptible to sedimentation
If the flow were supercritical at the entrance of the reservoir, it would be necessary to take into account the water depth and the flow rate as upstream boundary conditions

Summary

Introduction

The study of shallow flows involves a range of applications in Hydraulic Engineering domain and their respective areas of interest Among them, it can be highlighted the study of hydrodynamics and morphodynamics of shallow reservoirs, such as: (1) detention basins, often employed in urban drainage projects for flood control (PERSSON; WITTGREN, 2003; JANSONS; LAW, 2007); (2) stabilization ponds of sewage systems, whose sedimentation efficiency must be high so that they have adequate performance (OLUKANNI; DUCOSTE, 2011; CAMNASIO, 2012; LI et al, 2013); (3) aquaculture tanks, which demand a correct understanding of their hydraulic behavior, since they are associated with the development of fish, algae and crustacean cultures (MASALÓ, 2008); as well as many other water storage systems susceptible to sedimentation. If they are used as hydraulic sedimentation structures, the decantation of solids must be clearly maximized (DUFRESNE et al, 2010b)

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