Numerical Evaluation of the Influence of Geometric Aspects and Roughness on Hydrodynamic Behavior in a Shallow Rectangular Reservoir

Shallow reservoirs consist of hydraulic structures often adopted as engineering solutions governed by the principles of so-called shallow flows. Due to the complexity of these flows and phenomena related to them, there is a notable interest in carrying out studies aimed at expanding knowledge about their hydrodynamic behavior. The objective of this paper is to analyze numerically the influence of geometric changes and the roughness of walls and bottom on the flow patterns observed in a rectangular reservoir built for previous studies at the Hydraulic Research Center of the Federal University of Minas Gerais (CPH-UFMG, Brazil). At the time, three alternative locations were envisaged for coupling their inlet and outlet channels to the reservoir, which allowed the evaluation of different geometric combinations. For the numerical simulations, the Autodesk CFD finite element software version 2017 was used. Initially, simulations were performed to calibrate the numerical model adopted, selecting four of the geometric configurations evaluated in the laboratory. Subsequently, for three of these configurations, additional simulations were carried out contemplating the insertion of central islands with different formats and the roughness of the walls and the bottom of the reservoir. The results indicated that the insertion of an island, regardless of its shape, considerably altered the flow pattern observed for the symmetrical geometric configuration. However, the flow patterns referring to the asymmetrical geometric configurations did not change significantly. With respect to the alteration of the roughness of the reservoir, the flow patterns showed little influence of this parameter.