Investigation of Flow Field Around Submerged Bell Mouth Groin: An Experimental Study

Year 2011, Volume: 3 Issue: 1, 55 - 70, 01.03.2011

M.j. Uddin M.m. Hossain

Abstract

A study was undertaken to investigate the flow field around bell mouth groin in a large mobile bed physical
model facility (46m x 11 m). A total number of 24 test runs were conducted. Three different discharges and four
different angles and two groin conditions (submerged and non-submerged) was considered. All tests were
conducted for 8 hours duration in clear water condition. Velocity data have been collected forming grids in both
vertical and horizontal direction around the vicinity of the bell mouth groin. Velocity was measured at 0.2, 0.4,
0.6 and 0.8 depths from the water surface by forming grids. Change in flow conditions around bell mouth groin
for various test run have been analyzed non-dimensionally in longitudinal, lateral and vertical direction. The
streamwise velocity along lateral direction was found that the lateral shifting of maximum velocity away from
the head of the bell mouth groin. In most cases, streamwise vertical velocity in lower part of the channel is found
higher than that of upper part. Streamwise vertical velocity profile has been found variable with different
discharges and does not follow its natural logarithmic pattern. Velocity vector indicates that flow is steady at
upstream along longitudinal direction. The flow diverted at head of structure and flows through sides of
structure towards downstream. A circulation of flow has been observed around head of structure after diverting
of flow towards down. Immediately after rear front of structure, relatively weak circulation of flow has been
observed. In this paper the results of test runs conducted under submerged conditions for 1500
and 900
angles
are reported.

Keywords

Local scour, Submerged, Non-submerged, Bell mouth groin

References

• [1] Ahmad, M. 1953. Experiments on design and behavior of spur-dikes. Proc. Int. Hydraul. Convention. : 145–159
• [2] Breusers, H. N. C. 1991.Time scale of two-dimensional local scour. Proc. 12th Cong. IAHR 3: 275–282
• [3] Hossain, M.M. 1981. Study of River Bank Stabilization in a Bend by Groin. M.Sc. thesis, BUET, Dhaka, Bangladesh.
• [4] Ishigaki, T. & Baba, Y. 2004. Local Scour Induced by 3D Flow around Attracting and Deflecting Groins. Proceedings of Second International Conference on Scour and Erosion, Meritus Mandarin, Singapore: 301-308.
• [5] Khaleduzzaman, A.T.M. 2004. Experimental Study on River Course Stabilization and Restoration by using Groin-like Structures. Master thesis Kyoto University, Japan.
• [6] Kabir, M.A. 2007. An Experimental Study on the Effect of Submerged Vane on Scour and Flow around Abutment. M.Sc. Thesis, Department of Water Resources Engg., BUET, Dhaka.
• [7] Liu, M. K., Chang, F. M. & Skinner, M. M. 1961. Effect of bridge construction on scour and backwater. Report No. CER60-HKL22, Department of Civil Engineering, Colorado State University, Fort Collins, Colorado.
• [8] Muto, Y., Kitamura, K., Baba, Y. & Nakagawa, H. 2005. Field Measurement of Velocity Distribution in Groin Fields with ADCP. Annual Journal of Hydraulic Engineering, JSCE, 49.
• [9] Melville, B.W. 1997. Pier and abutment scour: integrated approach. Journal of Hydraulic Engineering, ASCE, 123(2), 125-136.
• [10] Rahman, M.M. & Muramoto, Y. 1999. Prediction of Maximum Scour Depth around Spur-Dike-Like Structures. Annual Journal of Hydraulic Engineering, JSCE, 43: 623- 628.
• [11] Rahman, M.M., Haque, M.A. & Alam, A.A. 2001. Flow Field Around Piers and Abutments at the Initiation of Scouring. Proceedings of the 1st International Conference on Civil Engineering, IEB and FEISCA, Chittagong, 2-3 Nov. pp.403-410.
• [12] Rahman, M.M., Haque, M.A. & Islam, M.S. 2002. Flow and Scouring around Piers and Abutments. 13th IAHR-APD Congress, Singapore, 280-283.
• [13] Richardson, E.V., Simons, D.B., Karaki, S. & Stevens, M.A., 1975. Highways in river environment. Hydraulic and Environmental Design Considerations, Engineering Research Center, Colorado State University, Fort Collins, Co.
• [14] Shields Jr., F.D., Cooper, C.M. & Knight S.S. 1995. Experiment in Stream Restoration. Journal of Hydraulic Engineering, ASCE, 121(6): 494-502.
• [15] Uijttewaal, W.S.J., Lehman, D. & Van Mazijk, A. 2001. Exchange Process Between a River and Its Groin Fields: Model Experiment. Journal of Hydraulic Engineering, Vol. 127, No 11, pp.122-125.