Author(s): Erik F. R. Bollaert

Linked Author(s): Erik Bollaert

Keywords: fluid-solid numerical coupling; jets; plunge pool scour

Abstract: A novel approach for detailed numerical assessment of rock scour formation in plunge pools or unlined channels downstream of hydraulic structures has been developed by Bollaert (2022). The approach is based on an automated numerical coupling between the hydraulics of a turbulent flow environment and the bathymetric evolution with time of the rocky bottom that is being scoured. Benefitting from a dedicated, user customizable interface, this coupling constitutes a cutting-edge tool available to engineers for real-life applications and projects. Detailed flow hydraulics are computed by FLOW-3D®, allowing sound implementation of air entrainment and defining the main flow parameters at the water-rock interface, such as time-averaged dynamic pressures, RMS (Root-Mean-Square) values of pressure fluctuations, time-averaged flow velocities and flow depths, shear stress, air entrainment, and so on. Bathymetric evolution with time of the eroding rock mass is computed by the rocsc@r® software, a cloud-based digital tool implementing the latest and most widely used computational methods for scour prediction. The paper presents an application of this novel approach to two different cases of jet impact. The first case concerns a free overflowing rectangular jet impinging into a plunge pool, while the second case deals with a horizontal high-velocity jet issuing from a bottom outlet of a dam. For both cases, the most relevant parameters are pointed out, as well as the results for different computational methods and CFD parameters. A parametric comparison is made with the theory of 2D jet diffusion in a plunge pool for the first case, and with the theory of submerged wall jets and hydraulic jumps for the second case.

DOI: https://doi.org/10.3929/ethz-b-000675921

Year: 2024