The importance of creating dynamically-scaled models of aquatic vegetation in the laboratory

Maryam Abdolahpour, Marco Ghisalberti, P. Lavery, K. McMahon

Research output: Chapter in Book/Conference paperConference paper

Abstract

Physical modelling of vegetated flows is an essential component of process-based investigations into vegetation
ecohydraulics. The vast majority of research into vegetated flows has employed rigid model vegetation, so that
the canopy’s geometry (i.e. its height and frontal area) is invariant and easy to quantify. Here, we demonstrate
that embedding realism (in the form of flexibility and buoyancy) in the model vegetation can have a profound
impact on the hydrodynamics. Specifically, we compare rates of vertical mixing in two types of model canopy
(with identical heights and frontal areas) subjected to oscillatory flow over a range of realistic wave heights and
periods. The two types of canopy were: (1) a rigid canopy consisting of wooden dowels, and (2) an array of
flexible, buoyant model plants designed to mimic a meadow of the seagrass Posidonia australis. Dynamic
similarity between the model and real seagrass was achieved by matching the two dimensionless ratios of the
dominant forces that govern plant motion (rigidity, buoyancy and drag). Results demonstrate a significant
difference in flow structure between the two canopies and a significant reduction in the rate of vertical mixing in
a flexible canopy, relative to the rigid analogue. Thus, while the use of dynamically-scaled vegetation models
adds a layer of modelling complexity, it represents a step towards a more faithful recreation of flow and mixing
in these systems.
Original languageEnglish
Title of host publicationProceedings of the 11th International Symposium on Ecohydraulics
EditorsJ.A. Webb, J.F. Costelloe , R. Casas-Mulet, J.P. Lyon , M. Stewardson
Place of PublicationMelbourne, Australia
PublisherEngineers Australia
ISBN (Print)9780734053398
Publication statusPublished - 2016
Event11th International Symposium on Ecohydraulics - Melbourne, Australia
Duration: 7 Feb 201612 Feb 2016

Conference

Conference11th International Symposium on Ecohydraulics
CountryAustralia
CityMelbourne
Period7/02/1612/02/16

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Abdolahpour, M., Ghisalberti, M., Lavery, P., & McMahon, K. (2016). The importance of creating dynamically-scaled models of aquatic vegetation in the laboratory. In J. A. Webb, J. F. Costelloe , R. Casas-Mulet, J. P. Lyon , & M. Stewardson (Eds.), Proceedings of the 11th International Symposium on Ecohydraulics [Paper 25992] Melbourne, Australia: Engineers Australia.