Flow Structure within a Vegetation Patch in an Experimental Flume

Document Type : Research Article


1 PhD Student, Department of Water Engineering, Isfahan University of Technology, Isfahan, Iran

2 Professor, Department of Civil Engineering, Iran University of Science and Technology, Tehran, Iran


Submerged vegetation patch plays a significant role in flow structures in river engineering. Although the existing theories of mixing layer can be applied to investigate the interaction of vegetation patch and flow, the effect of developing flow over small patches has not been yet considered in the literature. This experimental study applies the mixing -layer theory over artificial vegetation patch for two flow discharges 21 and 29 l/s. The results reveal that the mixing-layer thickness over the vegetation patch follows a logarithmic trend for developing and fully developed flow regions and the diffusion coefficient is less than the reported values in literature due to the limitation of vertical development of the mixing layer width by the bed and small canopy height. Also, there is a reasonable agreement between the measured values with the estimated ones by the mixing- layer over vegetation patch. The convex Reynolds stress distribution calls for more consideration in estimation roughness coefficient and sediment transport over vegetation patch under developing flow. 


حمیدی­فر، ح.؛ امید، م. ح. و کشاورزی، ر. (1394). "بررسی اثر پوشش گیاهی مستغرق و غیرمستغرق پهنه سیلابی بر ضریب اختلاط عرضی آلاینده‌ها". مجله هیدرولیک، دوره 10، شماره 1، ص‌ص. 13-23.
Afzalimehr, H.and Dey, S. (2009). “Influence of bank vegetation and gravel bed on velocity and Reynolds stress distributions”. Int. J. Sediment Res. 24(2), pp. 236–246.
Afzalimehr, H.; Moradian, M.; Sui, J. and Gallichand, J. (2015). “Effect of adverse pressure gradient and vegetated banks on flow structure”. J. River Res. Appl. 4(4), pp. 1-9.
Aberle, J. and Järvelä, J. (2015). Hydrodynamics of vegetated channels, In Rivers – physical, fluvial and environmental processes. In: Rowiński,P., Radecki-Pawlik, A.( Eds.): GeoPlanet: Earth and Planetary Sciences, Springer International Publishing, pp. 519-541.
doi: 10.1007/978-3-319-17719-9.
Carollo, F. G.; Ferro, V. and Termini, D. (2002). “Flow velocity measurment in vegetated Channels”. J. Hydraul. Eng. 128(7), pp. 664-673.
Chu, V. H. and Babarutsi, S. (1988). “Confinement and bed friction effects in shallow turbulent mixing layers”. J. Hydraul. Eng. 114, pp. 1257-1274.
Folkard, A. (2005). “Hydrodynamics of model Pasidonia oceanica patch in shallow water”. Limnol. Oceanogr. 50(5), pp. 1592–1600.
Folkard, A.M. (2011). “Flow regimes in gaps within stands of flexible vegetation: laboratory flume simulations”. Environ. Fluid Mech. 11, pp. 289-306.
Ghisalberti, M. and Nepf, H. (2002). “Mixing layers and coherent structures in vegetated aquatic flows”. J. Geophys. Res. 107 (C2). doi: 10.1029/2001JC000871.
Graf, W.H. and Altinkar, M.S. (1998). Fluvial hydraulics: flow and transport processes in channels of simple geometry. John Willey and Sons, Chichester. England.
Hamidifar, H.; Omid, M. H. and Keshavarzi, A. (2016). “Kinetic energy and momentum correction coefficients in straight compound channels with vegetated floodplain”, J. Hydrol. 537, pp. 10-17.
Marjoribanks, T. I.; Hardy, R. J.; Lane, S. N. and Tancock, M. J. (2016). “Patch-scale representation of vegetation within hydraulic models”. Earth. Surf. Proc. Land. 42, pp. 699–710.
Marjoribanks, T.; Parson, D.R. and Lane, S. (2016). “Does the canopy mixing layer model apply to hightly flexible aquatic vegetation? Insights from numerical modeling”. Environ. Fluid. Mech. 17 (2), pp. 277-301. doi:10.1007/s10652-016-9482-z.
Michalke, A. (1965). “Spatially growing disturbances in an inviscid shear layer”. J. Fluid. Mech. 23, pp. 521-544.
Nepf, H. (2012). “Hydodynamic of vegetated channels”. J.Hydraul. Res. 50(3), pp. 262-279.
Nepf, H. and Vivoni, E. (2000). “Flow structure in depth-limited, vegetated flow”. J. Geophys. Res. 105(C12), pp. 28547–28557.
Ortiz, A.C.; Ashton, A. and Nepf, H. (2013). “Mean and turbulent velocity field near rigid and flexible plants and the implication for deposition”. J. Geophys. Res. Earth. Surf. 118, pp. 2585-2599.
Pope, S. B. (2000). Turbulent Flows. Cambridge University Press.
Sinsicalchi, F.; Niora, V. and Albera, J. (2012). “Plant patch hydrodynamics in streams: Mean flow, turbulence and drag forces”. Water. Resour. Res. 48, W01513.
Sukhodolov, A. and Sukhodolova, T. (2006). “Evolution of mixing layers in turbulent flow over submerged vegetation: Field experiments and measurment study”. In: River Flow. Edited by Ferreira, R.M. L. et. al. proc. of 3rd International Conference on Fluvial Hydraulics, 6-8 September, Lisbon, Portugal, pp. 525-534.
Sukhodolov, A.N. and Sukhodolova, T.A. (2010). “Case study: Effect of submerged aquatic plants on turbulence structure in Lowland River”. J. Hydraul. Eng. ASCE. 136(7), pp. 434-446.
Sukhodolov, A. N.; Schnauder, I. and Uijttewaal, W. S. J. (2010). “Dynamics of shallow lateral shear layers: Experimental study in a river with a sandy bed”. Water Resour. Res. 46, W11519. doi:10.1029/2010WR009245
Sukhodolova, T. A. and Sukhodolov, A. N. (2012). “Vegetated mixing layer around a finite-size patch of submerged plants: 1. Theory and field experiments”. Water. Resour. Res. 40.W10533.
Sukhodolov, A. and Sukhodolova, T. (2012). “Vegetated mixing layer around a finite-size patch of submerged plants: 2. Turbulence and coherent structures”. Water Resour. Res. 48, W12506. doi:10.1029/2011WR011805
Wolman, M. G. (1954). “A method of sampling coarse river bed material”. Trans. AGU., 35(6), pp. 951–956.
Zong, L. and Nepf, H. (2011). “Spatial distribution of deposition within a patch of vegetation”. Water. Resour. Res. 47. W03516.
  • Receive Date: 09 June 2017
  • Revise Date: 16 August 2017
  • Accept Date: 22 August 2017
  • First Publish Date: 23 October 2017