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بررسی آزمایشگاهی تاثیر ارتفاع فرم بستر دیون بر ضریب زبری مانینگ | ||
| تحقیقات مهندسی سازه های آبیاری و زهکشی | ||
| دوره 23، شماره 87، آبان 1401، صفحه 99-118 اصل مقاله (1.09 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22092/idser.2022.359908.1522 | ||
| نویسندگان | ||
| مرضیه بادزن چین1؛ محمد بهرامی یاراحمدی* 2؛ محمود شفاعی بجستان3 | ||
| 1دانشجوی کارشناسی ارشد مهندسی عمران-آب و سازه های هیدرولیکی دانشکده مهندسی آب و محیط زیست دانشگاه شهید چمران اهواز، اهواز، ایران. | ||
| 2استادیار گروه سازه های آبی دانشکده مهندسی آب و محیط زیست دانشگاه شهید چمران اهواز، اهواز، ایران | ||
| 3استاد گروه سازه های آبی دانشکده مهندسی آب و محیط زیست دانشگاه شهید چمران اهواز، اهواز، ایران. | ||
| چکیده | ||
| معادلۀ مانینگ معروفترین معادلۀ تعیین مقاومت جریان در جریانهای ماندگار و یکنواخت است. میزان مقاومت جریان در مجاری باز علاوه بر اندازۀ ذرات رسوبی به نوع فرم بستر و خصوصیات هندسی آن بستگی دارد. روابط متعددی برای تعیین زبری اندازۀ ذره وجود دارد ولی تعیین میزان زبری فرم بستر کمتر بررسی شده است. مروری بر تحقیقات نشان می دهد که در زمینۀ اثر ارتفاع فرم بستر دیون بر ضریب زبری مانینگ تاکنون مطالعه نشده است. در تحقیق حاضر به بررسی اثر فرم های با ارتفاع 1، 2، 3 و 4 سانتیمتر و طول ثابت 25 سانتیمتر بر ضریب زبری مانینگ در یک فلوم مستقیم با 5 دبی و 5 شیب بستر پرداخته شده است. نتایج بررسی ها نشان داد که با افزایش ارتفاع فرم بستر و پارامتر استغراق نسبی ( Δ/λ)، ضریب زبری مانینگ افزایش می یابد. ضریب زبری مانینگ دیون های با ارتفاع 2، 3 و 4 سانتیمتر بهطور متوسط به ترتیب 16، 31 و 55 درصد بیش از ضریب زبری مانینگ فرم بستر با ارتفاع 1 سانتیمتر است. | ||
| کلیدواژه‌ها | ||
| ارتفاع فرم بستر؛ دیون؛ ضریب زبری مانینگ؛ مقاومت جریان؛ رودخانه آبرفتی | ||
| عنوان مقاله [English] | ||
| Experimental Study of the Effect of the Dune Bed Form Height on Manning's Roughness Coefficient | ||
| نویسندگان [English] | ||
| Marzieh Badzanchin1؛ mohammad bahrami yarahmadi2؛ Mahmood Shafai Bajestan3 | ||
| 1M.Sc. Student in Civil Engineering (Water & Hydraulic Structures), Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran. | ||
| 2Assistant Professor, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran | ||
| 3Professor, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran. | ||
| چکیده [English] | ||
| Extended Abstract Introduction Manning's equation is the most popular equation to determine the flow resistance in the steady and uniform flows. The amount of flow resistance in alluvial rivers depends on the type of bed form and its geometrical characteristics. In ripple and dune bed forms, which are formed at Froude numbers less than one (lower flow regime), the flow separation from their crest is the main factor of flow resistance (Shafai Bajestan, 2008; Julien, 2010). The effect of bed form on flow resistance have been studied by few researchers such as: Talebbeydokhti et al. (2006), Omid et al. (2010), Nasiri Dehsorkhi et al. (2011), Chegini and Pender (2012), Kabiri et al. (2014), Samadi-Boroujeni et al. (2014), Kwoll et al. (2016), and Heydari (2020). However, no research has been observed regarding the effect of the dune bed form height on Manning's roughness coefficient. Therefore, the main goal of the present study is to investigate the effect of dunes with different height of 1, 2, 3, and 4 cm on Manning's roughness coefficient in a straight flume under different discharges and bed slopes. Methodology The experiments were performed in a straight flume of 12 m in length and 0.30 m wide (Figure 1). In this study, different flow discharge of 10, 15, 20, 25, and 30 l/s and different bed slopes of 0.00001, 0.0001, 0.0005, 0.001, and 0.0015 were tested. Each dune was made in an asymmetric triangular shape with cement-sand mortar. The dune's height was equal to 1, 2, 3, and 4 cm, and the its length was selected as 25 cm. After each dune was built, the sediment with average size (d50) of 0.45 mm was glued to its surface. The total number of experiments in the present study was 100. Dune bed form dimensions were in lower flow regime. All the experiments were carried out at lower flow regime with, the Froude number values ranged from 0.44 to 0.7. Results and discussion Figure 4 shows the variation of the Manning's roughness coefficient against relative submergence (y/Δ) for dunes with a height of 1 cm. This figure shows that, with increasing relative submergence and bed slope, Manning's roughness coefficient decreased. Figure 5 shows the changes in the Manning's roughness coefficient against Froude number for dunes with different heights (slope of 0.0001). It can be seen that as the Froude number increased, the Manning's roughness coefficient decreased. Figure 7 illustrates the effect of Δ/λ on the Manning's roughness coefficient. This figure shows that the Manning's roughness coefficient increased with increasing Δ/λ. Calculations showed that the Manning's roughness coefficient in dunes with Δ/λ = 0.08, 0.12, and 0.16 was, on average, 17, 30, and 55% more than dune with Δ/λ = 0.04, respectively. Figure 8 shows the effect of the dune bed form height on the Manning's roughness coefficient. By increasing bed form height, Manning's roughness coefficient increased. Calculations showed that the Manning's roughness coefficient in dunes with height of 2, 3, and 4 cm was, on average, 16, 31, and 55% more than dune with a height of 1 cm, respectively. Conclusions The results of this study shows that with increasing the Froude number and the relative submergence (y/Δ), the flow resistance or Manning's roughness coefficient decreases. Moreover, the increase in the Δ/λ and the bed form height leads to an increase in Manning's roughness coefficient. Calculations showed that the Manning's roughness coefficient in dunes with height of 2, 3, and 4 cm was, on average, 16, 31, and 55% more than dune with a height of 1 cm, respectively. In addition, the form Manning's roughness coefficient (nb'') for dunes with heights of 1, 2, 3, and 4 cm is, on average, 30.7, 40.2, 46. 5, and 53.4% of the total Manning's roughness coefficient (nb), respectively. | ||
| کلیدواژه‌ها [English] | ||
| Bed form height, Dune, Manning', s roughness coefficient, Flow resistance, Alluvial river | ||
| مراجع | ||
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Afzalimehr, H. & Anctil, F. (1998). Estimation of gravel-bed river flow resistance. Journal of Hydraulic Engineering, 124 (10), 1054-1058. Afzalimehr, H., Singh, V.P. & Fazel Najafabadi, E. (2010). Determination of form friction factor. Journal of Hydrologic Engineering, 15(3), 237-243. Bahrami Yarahmadi, M. & Shafai Bejestan, M. (2011). Experimental study of the effect of sediment particles shape on Manning's coefficient. Journal of Water and Soil, 25(1), 51-60. (In Persian) Chegini, A.H.N. & Pender, G. (2012). Determination of small size bed load sediment transport and its related bed form under different uniform flow conditions. WSEAS Transactions on Environment and Development, 8(4), 158-167. Daghigh, H., karami Khaniki, A. & Ali Akbari Bidokhti, A. (2017). Evaluation of sandy bed ripples geometry using physical model and correcting existed practical relations factors. Iranian Journal of Marine Technology, 4(1), 64-74. (In Persian) Davarpanah-Jazi, S., Kabiri-Samani, A.R. & Afzalimehr, H. (2016). Effects of straight-crested gravel bed-forms and vegetated banks on turbulent flow characteristics. Modares Civil Engineering Journal, 16(2), 103-115. (In Persian) Dey, S. (2014). Fluvial Hydrodynamics: Hydrodynamic and Sediment Transport Phenomena. Springer-Verlag Berlin Heidelberg, 687P. Esmaili, K., Kashefipour, S.M. & Shafaie Bajestan, M. (2009). The effect of bed form on roughness coefficient in unsteady flows using a combined numerical and laboratory method. Journal of Water and Soil, 23(3), 136-144. (In Persian) Ghasemi, M., Heidarpour, M. & Tabatabaei S.H. (2016). Investigation of distribution of velocity and turbulence intensity in presence of dunes and vegetation in a rectangular open channel. Journal of Hydraulics, 10(3), 1-14. (In Persian) Heydari, M. (2020). Experimental investigation of the effect of the ripple bed form on flow resistance coefficient in straight reaches. Master's thesis, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Iran. (In Persian) Heydari, M., Bahrami Yarahmadi, M. & Shafai Bejestan, M. (2022a). Experimental study of the effect of bed forms on Darcy-Weisbach friction coefficient in the straight open channels. Journal of Hydraulics, 17(1), 35-49. (in Persian) Heydari, M., Bahrami Yarahmadi, M. & Shafai Bejestan, M. (2022b). Experimental study of the effect of bed forms with different sediment sizes on bed shear stress. Journal of Water and Soil Science (JWSS). (in Persian) Jafari Meanaii, S. & Keshavarzi, E. (2007). Investigation of stress and kinetic energy on ripples in the bed of open channels. 6th Iranian Hydraulic Conference, September 4-13, Shahrekord University. (in Persian) Jarret R. D. (1984). Hydraulics of high gradient streams. Journal of Hydraulic Engineering, 110, 1519- 1539. Julien, P.Y. (2010). Erosion and sedimentation. 2nd edition, Cambridge University Press, 390P. Kabiri, F., Afzalimehr, H., Smart, G. & Rousseau, A.N. (2014). Flow over gravel dunes. British Journal of Applied Science & Technology, 4(6), 905-911. Kwoll, E., Venditti, J.G., Bradley, R.W. & Winter, C. (2016). Flow structure and resistance over subaquaeous high- and low-angle dunes. Journal of Geophysical Research: Earth Surface, 121, 545–564. Nasiri Dehsorkhi, E., Afzalimehr, H. & Singh, V. P. (2011). Effect of bed forms and vegetated banks on velocity distributions and turbulent flow structure. Journal of Hydrologic Engineering, 16(6), 495-507. Okhravi, S. & Gohari, S. (2020). Form friction factor of armored riverbeds. Canadian Journal of Civil Engineering, 47(11). https://doi.org/10.1139/cjce-2019-0103. Omid, M.H., Karbasi, M. & Farhoudi, J. (2010). Effects of bed-load movement on flow resistance over bed forms. Sadhana, 35(6), 681-691. Ranga-Raju, K.G. & Soni, J.P. (1976). Geometry of ripples and dunes in alluvial channels. Journal of Hydraulic Research, 14(3), 241-249. Roshani, E., Hossienzade Dalir, A., Farsadizade, D. & Salmasi, F. (2017). Study of width reduced transition effects on ripple bed form height in various hydraulic conditions. Journal of Water and Soil, 31(1), 28-39. (In Persian) Samadi-Boroujeni, H., Maleki, P., Fattahi-Nafchi, R. & Ketabdari, M.J. (2014). Experimental study on the effect of the parallel and flake ripple bed forms on the Manning roughness coefficient. Journal of Hydraulics, 8(4), 55-65. (In Persian) Shafai Bajestan, M. (2008). Basic theory and practice of hydraulics of sediment transport. Second edition, Shahid Chamran University of Ahvaz Press. 549P. (In Persian) Simons, D.B. & Richardson, E.V. (1966). Resistance to flow in alluvial channels. Geological survey Professional paper, 422-J. Talebbeydokhti, N., Hekmatzadeh, A.A. & Rakhshandehroo, G.R. (2006). Experimental modeling of dune bed form in a sand-bed channel. Iranian Journal of Science and Technology, Transaction B, Engineering, 30(B4), 503-516. Yang, C.T. (1996). Sediment transport: Theory and practice. McGraw-Hill, 396P. | ||
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