Analysis of the Flow in a Typified USBR II Stilling Basin through a Numerical and Physical Modeling Approach

Abstract

Adaptation of stilling basins to higher discharges than those considered for their design implies deep knowledge of the flow developed in these structures. To this end, the hydraulic jump occurring in a typified United States Bureau of Reclamation Type II (USBR II) stilling basin was analyzed using a numerical and experimental modeling approach. A reduced-scale physical model to conduct an experimental campaign was built and a numerical computational fluid dynamics (CFD) model was prepared to carry out the corresponding simulations. Both models were able to successfully reproduce the case study in terms of hydraulic jump shape, velocity profiles, and pressure distributions. The analysis revealed not only similarities to the flow in classical hydraulic jumps but also the influence of the energy dissipation devices existing in the stilling basin, all in good agreement with bibliographical information, despite some slight differences. Furthermore, the void fraction distribution was analyzed, showing satisfactory performance of the physical model, although the numerical approach presented some limitations to adequately represent the flow aeration mechanisms, which are discussed herein. Overall, the presented modeling approach can be considered as a useful tool to address the analysis of free surface flows occurring in stilling basins.

Numerical and physical modelling approaches to the study of the hydraulic jump and its application in large-dam stilling basins

“…When increasing the dam discharge capacity, the most challenging part from a technical and economical point of view is usually the energy dissipation structure [5].…”

“…The use of reduced scale physical models and the corresponding experimental campaigns constitutes the traditional approach to the study of the hydraulic jump and the design of large-dam stilling basins [5]. Despite the appearance of new modelling techniques, physical modelling remains indispensable for a rigorous study of complex flows such as the hydraulic jump, where the support of experimental data is crucial [12], [18], [19].…”

“…Furthermore, according to Hager [2], the design of stilling basins in large dams, or when the failure of the structure would mean considerable losses, should always be supported by a hydraulic physical model. Even for the previously mentioned typified stilling basins, despite their standardised design, the use of physical models must be considered as a useful tool, due to their obvious practical interest [5], [12].…”

“…This structure has proved its efficiency for energy dissipation purposes when compared to other designs [73], [80]. In addition, there is an important knowledge built on its performance as its use is widely spread all around the world [5]. Apart from the already mentioned research by Rahmeyer and Tajabadi et al, Padulano et al [83] conducted an experimental campaign to study the behaviour of the USBR II basin under different hydraulic conditions.…”

“…The results by these authors were used in section 5.5 to contrast the presented models. Moreover, a series of works directly related with the present research, were carried out to analyse the flow developed in this basin, from a physical and a numerical perspective [5], [85].…”