Author(s): Tais Yamasaki; Rebecca Hodge; Richard Hardy; Robert Houseago; Joel Johnson; Rob Ferguson; Elowyn Yager; Trevor Hoey; Stephen Rice; Christopher Hackney
Linked Author(s): Richard Hardy
Keywords: CFD free surface river roughness pressure drag
Abstract: Mapping in detail the pressure variations on a riverbed of rough, irregular topography is the precursor step to obtaining the form drag of different topographic features, their contribution to overall drag and their interaction for varying flow, ultimately refining predictions of flow resistance for rough-bed rivers. This study presents the hydrodynamic pressure distribution on a scaled model of the rough bed of River Garry, Scotland, obtained with Computational Fluid Dynamics (CFD). A high-fidelity topographic section of the riverbed was reconstructed at a 1:10 scale, and a range of flow conditions were simulated in a two-phase flow model. The ratio between the mean flow depth and the standard deviation of the bed elevation varied between 3.33 and 7.78. Negative pressure peaked at the crest of ridges, where bed elevation was high, except when a crest was within the wake of an upstream crest of higher elevation. Also, the pressure difference across the ridges was higher for increasing flow depth and velocity.
Year: 2025