Influência de parâmetros geométricos e hidráulicos na distribuição de velocidades em bacias rasas retangulares

Abstract

Shallow basins are structures where the flow depth is insignificant in relation to the horizontal dimensions. In these cases the velocity field governs the mechanisms of particle transport and sedimentation. Thus, an evaluation of this field allows predicting sedimentation zones, or the presence of dead zones. Examples of these structures can be found in retention basins, aquaculture tanks and some parts of rivers and estuaries. This work investigates the formation of different kinds of rectangular shallow water flows. The correlation between geometrical and physical characteristics of these basins (dimensions and roughness), their hydraulic characteristics (flow regime), and the kind of flow observed were verified. To simulate the hydraulic conditions in the shallow basins, the software Basement, developed by ETHZ in its version 2.5.3 was used. Finally, parameters of interest towards projecting rectangular shallow basins are proposed in order to form symmetrical or asymmetric flows. It is verified that certain values of the shape parameter and expansion ratio dictate the possibility that a symmetric or asymmetric flow field is formed. Thus, for values of shape parameter above 6,2 and expansion ratio above 10, symmetric fields rarely occur. The scenarios corresponding to the shape parameter equal to 7,2, Manning roughness coefficient equal to 0,012 and flows ranging from 0,5L/s to 3,4L/s where simulated computationally and also observed in an experimental apparatus built at the Hydraulic Research Center of UFMG, using large-scale particle image velocimetry (LSPIV). It was identified a similar flow type on the computational and experimental turbulent simulations. It is recommended, therefore, to extend the experimental tests further using the numerical model as a guide.