Investigation of the effect of permeable obstacles on salt density current head

Document Type : Research Paper

Authors

• mehdi derakhshannia ¹
• mehdi ghomeshi ²
• saied saeid Eslamian ³
• seyed mahmood kashefipour ²

¹ Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran.

² Department of Water Structures, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.

³ Department of Water Engineering, College of Agriculture, Isfahan University of Technology, Isfahan, Iran.

10.30495/wej.2021.26173.2269

Abstract

Density currents are often the main cause of sediment transport in deep water and reservoirs. To prevent sedimentation in critical locations of dams, various methods have been proposed, including placing obstacles in the path of these currents. in this study, the effect of discharge, inlet concentration, slope and height of trapezoidal permeable obstacle on the behavior of density current has been investigated . 72 experiments were performed with variable discharge of 1, 1.5, and 2 liters per second and variable concentrations of 10 and 15 g/l, slope of 0.5%, 1% and 1.5% and obstacle height of 1,1.5 and 2 times the body of density current. The percentage of flux reduction was determined and the effect of other parameters was evaluated. The results showed that slope, concentration and inlet discharge are the factors affecting the momentum and by increasing each of these parameters, the efficiency of obstacle with heights of 1 and 1.5 times body density current decreases. In case of obstacle with a height of 2 times the body, when the current collides with the obstacle, there is a lot of turbulence, which decreases the momentum of the current, and complete control is performed. Thus, the average percentage of flux reduction for the dimensionless ratio of height 1 is about 38%, for the dimensionless ratio of height 1.5 is about 52% and for the dimensionless ratio of height 2 is about 86%. Finally, linear and nonlinear regression of the average percentage of flux reduction data was obtained.

Keywords

• Density currents
• Permeable obstacle
• Head flux
• Momentum

20.1001.1.20086377.1400.14.50.3.3

---

References

1. Assier RS, C. M, P. H. Numerical Simulation of Submarine Landslides and Their Hydraulic Effects. J Waterw Port, Coastal, Ocean Eng. 1997 Jul 1;123(4):149–57.
2. Li G, Piper DJW, Campbell DC, Mosher D. Turbidite deposition and the development of canyons through time on an intermittently glaciated continental margin: The Bonanza Canyon system, offshore eastern Canada. Mar Pet Geol. 2012;29(1):90–103.
3. Stagnaro M, Bolla Pittaluga M. Velocity and concentration profiles of saline and turbidity currents flowing in a straight channel under quasi-uniform conditions. Earth Surf Dyn. 2014 Mar 25;2(1):167–80.
4. Toniolo H, Parker G, Voller V, Beaubouef RT. Depositional Turbidity Currents in Diapiric Minibasins on the Continental Slope: Experiments—Numerical Simulation and Upscaling. J Sediment Res. 2006 May 1;76(5):798–818.
5. Dengler AT, Wilde P, Noda EK, Normark WR. Turbidity currents generated by Hurricane Iwa. Geo-Marine Lett. 1984;4(1):5–11.
6. Nomura S, Hitomi J, De Cesare G, Takeda Y, Yamamoto Y, Sakaguchi H. Sediment mass movement of a particle-laden turbidity current based on ultrasound velocity profiling and the distribution of sediment concentration. Geol Soc London, Spec Publ. 2019;477(1):427–37.
7. De Cesare G, Oehy C, Schleiss A. Experiments on turbidity currents influenced by solid and permeable obstacles and water jet screens. In: 6th ISUD-International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering. Czech Technical University in Prague-Institute of Hydrodynamics AS CR, vvi; 2008.
8. Davoodi L, Shafai Bejestan M. Application of submerged vanes for sediment control at Intakes from Irrigation trapezoidal channels. Water Irrig Manag. 2012;1(2):59–71. [In Persian].
9. Nasrollahpour R, Ghomeshi M. Effect of roughness geometry on characteristics of density currents head. Indian J Sci Technol. 2012;5(12):3783–7.
10. Oshaghi MR, Afshin H, Firoozabadi B. Experimental investigation of the effect of obstacles on the behavior of turbidity currents. Can J Civ Eng. 2013 Feb 25;40(4):343–52.
11. Abhari MN, Iranshahi M, Ghodsian M, Firoozabadi B. Experimental study of obstacle effect on sediment transport of turbidity currents. J Hydraul Res. 2018 Sep 3;56(5):618–29.
12. Kooti F, Kashefipour SM. Sensitivity of the head velocity in density currents to the various initial conditions. ISH J Hydraul Eng. 2018 Jan 2;24(1):74–80.
13. Baghalian S, Ghodsian M. Experimental study on the effects of artificial bed roughness on turbidity currents over abrupt bed slope change. Int J Sediment Res. 2020;35(3):256–68.
14. Jahangir A, Esmaili K, Maghrebi MF. Experimental Investigation of Porosity, Installation Angle, Thickness and Second Layer of Permeable Obstacles on Density Current. Int J Eng. 2020;33(9):1710–20.
15. Jinchao X, Yun L, Guoxiang X, W. MB, H. MG. Numerical Simulation of Turbidity Current in Approach Channels with a Closed End. J Waterw Port, Coastal, Ocean Eng. 2020 Sep 1;146(5):4020036.
16. Koohandaz A, Khavasi E, Eyvazian A, Yousefi H. Prediction of particles deposition in a dilute quasi-steady gravity current by Lagrangian markers: effect of shear-induced lift force. Sci Rep. 2020;10(1):16673.
17. Goodarzi D, Sookhak Lari K, Khavasi E, Abolfathi S. Large eddy simulation of turbidity currents in a narrow channel with different obstacle configurations. Sci Rep. 2020;10(1):12814.
18. Soler M, Colomer J, Folkard A, Serra T. Particle size segregation of turbidity current deposits in vegetated canopies. Sci Total Environ. 2020;703:134784.
19. Huang S, Huang W, Shen Q. Effects of Bottom Obstacle Structure on Density-Induced Flow. IOP Conf Ser Earth Environ Sci. 2020;455:12024.
20. Asghari Pari SA, Kashefipour SM, Ghomeshi M, Shafai-Bajestan M. Effects of obstacle heights on controlling turbidity currents with different concentrations and discharges. J Food, Agric Environ. 2010;8(2):930–5.
21. khosropour soleyman, Kashefipour SM, Daryaee M. Investigating the Effect of the Density and Pattern of Roughness Blocks with Obstacle on the Control of Density Current Head. J Hydraul. 2019;14(2):105–15. [In Persian].
22. Kordnaej M, Asgharipari SA, Sajadi MS, Shafaei Bajestan M. Laboratory comparison of the effect of porous obstacle and porous stepped obstacle in the control of density current. J Mar Sci Technol. 2017;16(4):86–96. [In Persian].
23. Zeynivand M, KashefiPour SM, Ghomeshi M. Laboratory Investigation The Effect of Porosity of Permeable Obstacle on Control of Gravity Current. J Irrig Sci Eng. 2017;40(1):13–24. [In Persian].
24. Mohammadi MAH, Pari SAA, Sajjadi SM. Experimental Investigation of the effects of Gabion Obstacle’s Height, Shape and distance of obstacle from entrance to Control the Turbidity Current. J Water Soil Conserv. 2016;23(4):251–65. [In Persian].

Asghari Pari SA, Mohagheghian SM. Numerical study of the effect of using plate obstacle and oblique columnar obstacles in controlling density current. Iran J Irrig Drain. 2015;9(2):357–66. [In Persian].