Turbulent Flow through Idealized Emergent Vegetation

Stoesser, Thorsten ORCID: https://orcid.org/0000-0001-8874-9793, Kim, S. J. and Diplas, P. 2010. Turbulent Flow through Idealized Emergent Vegetation. Journal of Hydraulic Engineering 136 (12) , pp. 1003-1017. 10.1061/(ASCE)HY.1943-7900.0000153

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Abstract

This paper presents results of several large-eddy simulations (LES) of turbulent flow in an open channel through staggered arrays of rigid, emergent cylinders, which can be regarded as idealized vegetation. In this study, two cylinder Reynolds numbers, RD=1,340 and RD=500, and three vegetation densities are considered. The LES of the lowest density and at RD=1,340 corresponds to a recently completed laboratory experiment, the data of which is used to validate the simulations. Fairly good agreement between calculated and measured first- and second-order statistics along measurement profiles is found, confirming the accuracy of the simulations. The high resolution of the simulations enables an explicit calculation of drag forces, decomposed into pressure and friction drag, that are exerted on the cylinders. The effect of the cylinder Reynolds number and the cylinder density on the drag and hence on the flow resistance is quantified and in agreement with previous experimental studies. Turbulence structures are visualized through instantaneous pressure fluctuations, isosurfaces of the Q-criterion and contours of vertical vorticity in horizontal planes. Analysis of velocity time signals and distributions of drag and lift forces over time reveals that flow and turbulence are more influenced by the vegetation density than by the cylinder Reynolds number.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Engineering
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering
Uncontrolled Keywords:	Vegetation, Turbulence, LES, Drag, Flow resistance, Coherent structures
Additional Information:	Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/0733-9429/ (accessed 25/02/2014)
Publisher:	ASCE
ISSN:	0733-9429
Date of First Compliant Deposit:	30 March 2016
Last Modified:	02 May 2023 16:06
URI:	https://orca.cardiff.ac.uk/id/eprint/36191

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