بررسی قوانین لگاریتمی وکولز در تراکم‌های مختلف پوشش گیاهی غیرمستغرق

نوع مقاله: مقاله کامل

نویسندگان

1 استاد دانشکده مهندسی عمران، دانشگاه علم و صنعت ایران، تهران

2 دانش‌آموخته کارشناسی ارشد مهندسی کشاورزی-سازه‌های آبی، دانشگاه صنعتی اصفهان، اصفهان

چکیده

پوشش گیاهی موجود در رودخانه­ها را می­توان از نظر ارتفاع گیاه نسبت به عمق آب، در دو گروه گیاهان مستغرق و غیرمستغرق دسته­ بندی کرد. در این مقاله از پوشش گیاهی غیرمستغرق نی در تراکم­ های مختلف، روی بستر شنی کانال آزمایشگاهی استفاده گردید. در این مطالعه شکل و سایر ویژگی­های گیاه نی در تمام عمق آب ثابت است و تأثیر حضور و تراکم آن روی نیم­رخ سرعت جریان و اعتبار قانون­های لگاریتمی و کولز بر نیم­رخ سرعت بررسی شده است. نتایج نشان می­دهد که در بخش داخلی لایه مرزی که در نزدیکی بستر واقع است، قانون لگاریتمی برای پوشش گیاهی با تراکم­های گوناگون معتبر است؛ هرچند میزان انحراف داده­ ها از این قانون در لایه خارجی بسیار بیشتر از بستر شنی بدون حضور پوشش گیاهی است. کاربرد قانون کولز در ناحیه خارجی بر خلاف بستر شنی در حالت پوشش گیاهی به ­دلیل توزیع نامتعارف نیم­رخ سرعت جریان و تشدید آشفتگی با افزایش تراکم پوشش گیاهی نامعتبر است.

کلیدواژه‌ها


کوچک زاده، ص. و یوسفی، ک. (1381). تئوری و کاربرد انتقال رسوب (ترجمه)، انتشارات دانشگاه تهران.

Afzalimehr, H. Barahimi, M. and Sui, j. (2017). “Non-uniform flow over cobble bed with submerged vegetation strip”, J. Water Management, ICE. UK, in press.

Afzalimehr, H. Moradian, M. Sui, J. and Gallichand, J. (2015). “Effect of adverse pressure gradient and vegetated banks on flow structure”, J. River Research and Applications. 4(4), pp. 1-9.

Afzalimehr, H, Bagheri, E. Gallichand, J. and Dufresne, L. (2014). “Cobble-bed concentration and vegetated banks: effects on flow”, Proc. of the Institution of Civil Engineers- Water Management. 167, pp. 206-218.

Afzalimehr, H. Fazel, E. and Ghalichand, J. (2012). “Effects of accelerating and decelerating flows in a channel with vegetated banks and gravel bed”, International J. Sediment Research, 27 (2), pp. 188-200.

Afzalimehr, H. (2010). “Effect of flow non-uniformity on velocity and turbulence intensities in flow over a cobble bed”, J. Hydrol. Process, 24, pp. 331-341.

Afzalimehr, H. Fazel, E. and Singh, V. P. (2010). “Effect of vegetation on banks on distributions of velocity and Reynolds stress under accelerating flow”, J. Hyd. Eng., 15(9), pp. 708-713.

Afzalimehr, H. Gallichand, J. Sui, J. and Bagheri, E. (2011). “Field investigation on friction factor in mountainous cobble-bed and boulder-bed Rivers”, International J. Sediment Research. 26(2), pp. 210-221.

Afzalimehr, H.and Dey, S. (2009). “Influence of bank vegetation and gravel bed on velocity and Reynolds stress distributions”, International J. Sediment Research. 24(2), pp. 236–246.

Afzalimehr,H. and Rennie, C.D. (2009). “Determination of bed shear stress using boundary layer parameters in a gravel-bed river”, J. Hydrological Sciences, 54(1), pp.147-159.

Afzalimehr, H. and Anctil, F. (2000). “Accelerating shear velocity in gravel bed channels”, J. Hydrol. Sci, 45(1), pp. 143-155.

Afzalimehr, H. and Anctil, F. (1999). “Velocity distribution and shear velocity behavior of decelerating flow over a gravel- bed. Journal of Canadian Civil Engineering”, 26(4), pp. 468-475.

Barenblatt, G.I. (1982). “Similarity, Self-Similarity and Intermediate Asymptotics”, Consultants Bureau: New York, N. Y.

Baptist, M. J. Babovic, V. Uthurburu, J. R. Keijzer, M. Uittenbogaard, R. E. Mynett, A. and Verwey, A. (2007). “On inducing equations for vegetation resistance”, J. Hydraul. Res. 45(4), pp. 435–50.

Cardoso, A. H. Graf, W. H. and Gust, G. (1990). “Uniform flow in a smooth open channel”, J. Hydraul. Res, 27(5), pp. 603-616.

Cheng, N. (2011). “Representative roughness height of submerged vegetation”, J. Water Resour. Res, 47(8), pp. 427-438.

Chanson, H. (2001). “The Hydraulics of Open Channel Flow, An Introduction”. Butterworth-Heinemann.

Coles, D. (1956). “The law of the wake in turbulent boundary layer”, J. Fluid Mech. 1, pp. 191-226.

Costanza, R. Arge, R. and Groot, R. (1998). “The value of the world’s ecosystem services and natural capital”, J. Ecol. Econ, 25(1), pp. 3–15.

Dey, S. (2014). “Fluvial hydrodynamics: Hydrodynamic and sediment transport phenomena”. Springer-Verlag, Berlin.

Fazel, E. Afzalimehr, H. and Sui, J. (2015). “Turbulence characteristics of favorable pressure gradient flows in gravel-bed channel with vegetated walls”, J. Hydrology and Hydromechanics, 63(2), pp. 154-163.

Francis, J. B. (1878). “On the cause of the maximum velocity of water flowing in open channels being below the surface”, Transactions of the American Society of Civil Engineers.  ASCE, 7(1), pp. 109-113.

Goring, D. G. and Nikora, V. L. (2002). “Despiking acoustic doppler velocimeter data”. J. Hydraulic Engineering, ASCE. 128(1), pp. 117-126.

Gil Montero, V.G. Romagnoli, M. García, C.M. Cantero, M. I. and Scacchi, G. (2014). “Optimization of ADV sampling strategies using DNS of turbulent flow”, J. Hydraulic Research, 52(6), pp. 862–869

Graf, W. H. and Altinakar, M. S. (1998). Fluvial hydraulics: Flow and transport processes in channels of simple geometry. Willey, Chichester. ISBN 0-471-97714-4.

Hinze, J. O. (1975). Turbulence. McGraw-Hill Book Co. New York.

Huai, W. X. Chen, G. and Zeng, Y. H. (2012). “Predicting apparent shear stress in prismatic compound open channels using artificial neural networks”, J. Hydroinform, 15(1), pp. 138-146.

Huai, W. X. Zeng, Y. H. Xu, Z. G. and Yang, Z. H. (2009). “Three-layer model for vertical velocity distribution in open channel flow with submerged rigid vegetation”, Adv. in Water Resour., 32(4), pp. 487–492.

Huthoff, F. Augustijn, D. C. M. and Hulscher, S. J. M. H. (2007). “Analytical solution of the depth-averaged flow velocity in case of submerged rigid cylindrical vegetation”, J. Water Resour. Res., 43(6), pp. 129-148.

Julien, P. Y. (2010). “Erosion and Sedimentation”, Cambridge University Press, Cambridge United Kingdom, 390 p.

Kironoto, B. A. (1992). “Turbulence characteristics of uniform and non-uniform, rough open channel flow”, Ph.D thesis. Ecole Polytechnique Federal de Lausanne, Switzerland.

Kironoto, B. A. and Graf, W. H. (1994). “Turbulence characteristics in rough uniform open channel flow”, Proceedings of the ICE-Water Maritime and Energy, 106, pp. 333–344.

Liu, D. Diplas, P. Fairbanks, J. and Hodges, C. (2008). “An experimental study of flow through rigid vegetation”, J. Geophys. Res.: Earth Surf. 113(F4).

Lopez, R. O. T. (2011). “An experimental investigation of drag and the turbulent flow structure in simulated and real aquatic vegetation”, Ph.D. thsise, Cornell University, USA.

MacVicar, B.J., and Roy, A.G. (2007). Hydrodynamics of a forced riffle pool in a gravel bed river: 1. Mean velocity and turbulence intensity. Water Resource Research, 43(12): W12401. doi:10.1029/2006WR005272.

Monty, J. P. Hutchins, N. Ng, H. C. H. Marusic, I. and Chong, M. S. (2009). “A comparison of turbulent pipe, channel and boundary layer flows”, J. Fluid Mech. 632, pp. 431–442.

Nakagawa, H. Tsunhimoto, T. and Shimizu, Y. (1991). “Turbulent flow whit small relative submergence. Fluvial hydraulics of mountain regions”, J. Lect. Notes Earth Sci, 37, pp. 33-44.

Nepf, H. M. (2012). “Flow and transport in regions with aquatic vegetation”, J. Annu. Rev. Fluid Mech, 44, pp. 123-142.

Nepf, H. M. White, B. Lightbody, A. and Ghisalberti, M. (2007). “Transport in aquatic canopies. In Flow and Transport Processes with Complex Obstructions”, Springer Netherlands. pp. 221-250.

Nezu, I. (1977). “Turbulence structures in open channel flow”, Ph.D thesis. Civil Engineering, Kyoto University, Japan.

Nezu, I. and Rodi, W. (1986). “Open channel flow measurements with a laser Doppler anemometer”, J. Hydraul. Eng, 112(5), pp. 335-355.

Nezu, I. and Nakagawa, H. (1993). “Turbulence in open channel flows”, Monograph of IAHR, A.A. Balkema publishers, Brookfield, USA.

Nikora, N. Nikora, V. and O'Donoghue, T. (2014). “Velocity profiles in vegetated open-channel flows: combined effects of multiple mechanisms”, J. Hydraul. Eng, 139(10), pp. 1021-1032.

Nikora, Y. and Goring, D. (2000). “Flow turbulence over fixed and weakly mobile gravel beds”, J. Hydraul. Eng. ASCE. 126(9), pp. 679-690.

Song, T.C. (1994). “Velocity and turbulence distribution in non-uniform and unsteady open - channel flow”, Ph.D. thesis, Ecole Polytechnique Federale de Lausanne, Switzerland.

Stoesser, T. and Nikora, V.I. (2008), “Flow structure over square bars at intermediate
submergence: Large Eddy Simulation study of bar spacing effect”, J. Acta Geophys. 56 (3), pp. 876-893.

Stone, B. M. and Shen, H. T. (2014). “Hydraulic resistance of flow in channels with cylindrical roughness”, J. Hydraul. Eng. 128(5), pp. 500-506.

Thibodeaux, K. G. (1994). “Review of Literature on the Testing of Point-Velocity Current Meters”, U.S. geological survey open-file report 94-123. 44 p.

Wolman, M. G. (1954). “A method of sampling coarse river bed material”, EOS, Transactions American Geophysical Union, 35(6), pp. 951-956.

Yang, S. Q. and Lee, J. W. (2007). “Reynolds shear stress distributions in a gradually varied flow”, J. Hydraul. Res, 45(4), pp. 462-471.

Zagarola, M. (1996). “Mean flow scaling in turbulent pipe flow”, Ph.D. thesis, Princeton University, Princeton, USA.