Simulation of turbulent flows in river confluences and meandering channels with a Cartesian 3D free surface hydrodynamic model

Abstract

Three-dimensional primitive equations (3DPE) become a reasonable approach in hydrodynamics in terms of computational costs when the length of the computational domain and/or computational time scales increases. However, given the simplified set of equations used in the analysis, results with 3DPE-based models are expected to be approximate and before attempting to reproduce complex natural flows they first need to be validated against more simple flows observed in laboratory settings. Here, the validity of Cartesian free-surface hydrodynamic models to reproduce three turbulent flows characteristic of river environments is tested: (1) the development of shallow mixing layers, (2) flow pass a lateral cavity and (3) flow in open channel with mild curvature. Errors between measured and modeled values were generally less than 10%, proving their validity to reproduce such turbulent flows and their potential for simulations in more complex natural environments, such it is the case of the confluence between the Ebro and Segre rivers into Ribarroja reservoir.