Author(s): F. D. Oliveira; M. W. Heredia

Linked Author(s): Marcelo Heredia Gómez

Keywords: Spillway dam; Delft3D model; three-dimensional model; hydrostatic; non-hydrostatic; sensitivity analysis

Abstract: Numerical modelling is an attractive alternative over physical modelling. However, sometimes both kind of techniques are coupled. This is the case of Hampaturi Dam in La Paz, Bolivia. A physical model was built for the optimization of the spillway. Hence, a numerical model was implemented with Delft3D computational model. Delft3D is a model based on two-dimensional flow equations (hydrostatic equations), and full three-dimensional equations (hydrostatic equations). Both modes were tested for the flow over the spillway, which includes a steep discharge channel that poses an additional difficulty. The goal of this research is to test the model (in both modes) on these flow conditions in order to determine the feasibility in applying Delft3D on this kind of structure. The model was calibrated and validated for both modes, hydrostatic and non-hydrostatic, by the variation of Manning’s roughness coefficient and eddy viscosity, reproducing the observed flow velocities and water depths. Following, a sensitivity analysis was carried out to determine the influence of different parameters in both modes, like: number of vertical layers, bed roughness and eddy viscosity. This analysis was executed by using an independent mesh solution. Results show a significant influence of the tested parameters. Then, the influence of the channel steepness on the performance of the model was tested. Results show that non-hydrostatic mode produces smooth flow profiles. Finally, it was observed that both modes can operate up to inclination angles of 60° for the discharge channel, setting an operation limit for Delft3D in this kind of structure.

DOI: https://doi.org/10.26077/4151-67ed

Year: 2022