Experimental Study on the Effect of the Parallel and Flake Ripple Bed Forms on the Manning Roughness Coefficient

Document Type : Technical Note

Authors

1 Associate Professor, Department of Water Engineering, Shahrekord University, Shahrekord, Iran

2 MSc. Student, Hydraulic Structures, Shahrekord University, Shahrekord, Iran

3 Assistant Professor, Department of Water Engineering, Shahrekord University, Shahrekord, Iran

4 Associate Professor Department of Civil Engineering, Amirkabir University, Tehran, Iran

Abstract

Estimation of the flow resistance is one of the most important parameters in the planning, design and operation of water resources projects, including water transfer and river system management. Bed forms, such as ripple, have significant effects on total roughness. In this paper, the effects of two types of ripples on the Manning coefficient was investigated. Experiments were performed in the Hydraulic Laboratory of Shahrekord University. Some relationships were obtained based on the geometric characteristics of the ripple bed forms and flow conditions using SPSS software. It was also observed that in the case of parallel ripple bed form, the roughness was about 47% more than that of plane bed and in the case of flake ripple bed form, the increasing rate was 43%. It was concluded that the Manning coefficient was significantly affected by the parallel shape of ripple bed form compared with the flake shape.

Keywords


بهرامی‌یاراحمدی، م. و شفاعی بجستان، م. (1390). "بررسی آزمایشگاهی اثر شکل ذرات رسوبی بستر بر ضریب زبری مانینگ"، نشریه آب و خاک (علوم و صنایع کشاورزی)، جلد 25، شماره 1، ص.ص. 51-60.
شفاعی بجستان، م. (1387). مبانی نظری و عملی هیدرولیک انتقال رسوب، انتشارات دانشگاه شهید چمران.
عطار، ش. (1387). "تأثیر شکل بستر شنی بر توزیع‌های سرعت جریان و تنش برشی"، پایان‌نامه کارشناسی ارشد آبیاری و زهکشی، دانشگاه صنعتی اصفهان.
کرباسی، م. (1384). "بررسی اثر حرکت بار بستر بر مقاومت هیدرولیکی جریان در حضور فرم­های بستر"، پایان‌نامه کارشناسی ارشد مهندسی سازه­‌های آبی، دانشکده کشاورزی، دانشگاه تهران.
Afzalimehr, H. and Anctil, F.( 1998). "Estimation of gravel-bed river flow resistance", Journal of Hydraulic Engineering 124(10), pp. 1054-1058.

Carling, P. A. (1999). "Subaqueous gravel dunes", Journal of Sedimentary Research, 69(3), pp. 534-545.

Chien, N. and Wan, Z. (1999). "Mechanics of sediment transport reston”, VA: ASCE Press. 913: pp. 195-245.
Joep, A. Storms Remke, L. Vandam and Suzanne, F. Leclair.( 1999). "Preservation of cross-sets due to migration of current ripples over aggrading and non- aggrading beds: comparison of experimental data with theory", Journal of International Association of Sedimentologists, 46(1), pp. 189-200.
Simons, D. B. and Richardson, E. V. (1966). "Resistance to flow in alluvial channels", USGS Professional, 422-61.
Talebbeydokhti, N. Hekmatzadeh, A.A and Rakhshandehroo, G.R. (2006). "Experimental modeling of dune bed form in a sand-bed channel", Iranian Journal of Science & Technology, Transaction B, Engineering. 30(4), pp. 503-516.
Yen, B. C. (2002). "Open channel flow resistance", Journal of Hydraulic Engineering, 128 ( 1), pp. 20-39.