Author(s): Carsten Thorenz

Linked Author(s): Carsten Thorenz

Keywords: Hydraulic structures; CFD; OpenFOAM; boundary conditions; water level; flowrate

Abstract: In the last decades, three-dimensional numerical modelling of fluid flows, the so-called computational fluid dynamics (CFD), has evolved from a primarily scientific topic to a widely used engineering tool. Within the Federal Waterways Engineering and Research Institute (BAW), different CFD tools have been tested, validated and used for research and consultancy in the past. Since 2010, The usage of OpenFOAM at the BAW for consultancy was facilitated by providing an in-house toolset, which largely simplifies the modelling of flow at hydraulic structures. While the computation of confined flow in ducts and culverts is relatively easy to handle, the flow of water with a free surface in arbitrary geometries like hydraulic structures poses additional challenges. The provided boundary conditions of OpenFOAM do not allow an easy specification of the hydraulic conditions in the way they are typically set in physical models (i.e. the prescription of water levels and flow rates). Two in-house developed boundary conditions are described here: The first allows the specification of fixed, but unsteady, flowrates with varying water levels. This boundary condition dynamically computes the prescribed velocity field from the current water level and the desired flowrate. The second boundary prescribes the water level at a boundary. The numerical background of the boundary conditions is briefly explained from an engineering point of view and an application example is presented.

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

Year: 2024