Flow through a very porous obstacle in a shallow channel

Creed, M. J. , Draper, S., Nishino, T. and Borthwick, A. G. L. (2017) Flow through a very porous obstacle in a shallow channel. Proceedings of the Royal Society of London Series A: Mathematical, Physical and Engineering Sciences, 473(2200), 20160672. (doi: 10.1098/rspa.2016.0672) (PMID:28484321)

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Abstract

A theoretical model, informed by numerical simulations based on the shallow water equations, is developed to predict the flow passing through and around a uniform porous obstacle in a shallow channel, where background friction is important. This problem is relevant to a number of practical situations, including flow through aquatic vegetation, the performance of arrays of turbines in tidal channels and hydrodynamic forces on offshore structures. To demonstrate this relevance, the theoretical model is used to (i) reinterpret core flow velocities in existing laboratory-based data for an array of emergent cylinders in shallow water emulating aquatic vegetation and (ii) reassess the optimum arrangement of tidal turbines to generate power in a tidal channel. Comparison with laboratory-based data indicates a maximum obstacle resistance (or minimum porosity) for which the present theoretical model is valid. When the obstacle resistance is above this threshold the shallow water equations do not provide an adequate representation of the flow, and the theoretical model over-predicts the core flow passing through the obstacle. The second application of the model confirms that natural bed resistance increases the power extraction potential for a partial tidal fence in a shallow channel and alters the optimum arrangement of turbines within the fence.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Creed, Dr Maggie
Authors: Creed, M. J., Draper, S., Nishino, T., and Borthwick, A. G. L.
College/School:College of Science and Engineering > School of Engineering > Infrastructure and Environment
Journal Name:Proceedings of the Royal Society of London Series A: Mathematical, Physical and Engineering Sciences
Publisher:The Royal Society
ISSN:1364-5021
ISSN (Online):1471-2946
Published Online:26 April 2017

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