Evaluation of Hydrodynamic Consequences for Horseshoe Vortex System developing around two eccentrically arranged Identical Piers of Diverse Shapes

다국어 초록 (Multilingual Abstract)

This research provides experimental outcomes of hydrodynamic flow formations around two square piers of same widthpositioned in inline front and eccentric rear arrangement with a constant longitudinal spacing and eccentricity. Measurements ofinstantaneous velocities in polar coordinate system were taken by a Doppler type acoustic velocimeter. The distributions and contourprofiles of time mean tangential, radial and vertical velocities, kinetic energy and intensities due to turbulence are presented at fiveazimuth angles 0°, -45°, 45°, -90° and 90° in vertical planes. From time mean velocity fields, velocity vectors were determined andutilised to explain added flow features. Horseshoe vortices vorticity and the strength (circulation) are resolved by usingcomputational hydrodynamics method. The preset outcomes are compared with previous researches where cylindrical and triangularshaped piers were used at same experimental conditions. The arrangement of square piers and the interfering among wake andhorseshoe vortices for inline-front and eccentric-rear piers, respectively - take part in a major role for making and forming biggerdepth of scour near eccentrically positioned rear pier. Due to bluff body existence, friction drag becomes less effective than thepressure drag. Horseshoe vortex strength for eccentric-rear pier is observed greater than strength for inline-front pier.

참고문헌 (Reference)

1 Michael, S. A., "Wake vortex scour at bridge piers" 117 (117): 891-904, 1991

2 Das, S., "Variations of clear water scour geometry at piers of different effective widths" 38 (38): 97-111, 2014

3 Das, S., "Turbulence flow field around two eccentric circular piers in scour hole" 13 (13): 343-361, 2015

4 Dargahi, B., "The turbulent flow field around a circular cylinder" 8 (8): 1-12, 1989

5 Zdravkovich, M. M., "The effects of interference between circular cylinders in cross flow" 1 (1): 239-261, 1987

6 Ettema, R., "Similitude of large scale turbulence in experiments on local scour at cylinders" 132 (132): 33-40, 2006

7 Roulund, A., "Numerical and experimental investigation of flow and scour around a circular pile" 534 : 351-401, 2005

8 Raudkivi, A. J., "Loose boundary hydraulics" A.A. Balkema 1998

9 Breusers, H. N. C., "Local scour around cylindrical piers" 15 (15): 211-252, 1977

10 Das, S., "Kinematics of horseshoe vortex in a scour hole around two eccentric triangular piers" 41 (41): 296-317, 2014

11 Ataie-Ashtiani, B., "Flow field around single and tandem piers" 90 (90): 471-490, 2013

12 Ataie-Ashtiani, B., "Flow field around side-by-side piers with and without a scour hole" 36 : 152-166, 2012

13 Melville, B. W., "Flow characteristics in local scour at bridge piers" 15 (15): 373-380, 1977

14 Graf, W. H., "Experiments on flow around a cylinder: The velocity and vorticity fields" 36 (36): 637-653, 1998

15 Ataie-Ashtiani, B., "Experimental investigation of clear-water local scour at pile groups" 132 (132): 1100-1104, 2006

16 Unger, J., "Down-flow and horseshoe vortex characteristics of sediment embedded bridge piers" 42 (42): 1-19, 2007

17 Das, S., "Comparison of local scour characteristics around two eccentric piers of different shapes" 41 (41): 1193-1213, 2016

18 Das, S., "Comparison of kinematics of horseshoe vortex at a flat plate and different shaped piers" 42 (42): 418-448, 2015

19 Yilmaz, M., "Clear-water scour evolution at dual bridge piers" 44 : 298-307, 2017

20 Raudkivi, A. J., "Clear-water scour at cylindrical piers" 109 (109): 338-350, 1983

21 Das, S., "Clear water scour geometry around circular piers" 20 (20): 479-492, 2014

22 Dey, S., "Clear water scour at circular piers: A model" 121 (121): 869-876, 1995

23 Das, S., "Circulation characteristics of horseshoe vortex in scour region around circular piers" 6 (6): 59-77, 2013

24 Dey, S., "Characteristics of horseshoe vortex in developing scour holes at piers" 133 (133): 399-413, 2007

25 Das, S., "A study of wake vortex in the scour region around a circular pier" 40 (40): 42-59, 2013