EXPERIMENTS ON THE DYNAMICS OF DENSITY CURRENTS
DOI:
https://doi.org/10.11113/jt.v78.9697Keywords:
Turbidity current, velocity profiles, front velocity, bottom slope, concentrationAbstract
Density currents occur when fluid of one density propagates along a horizontal boundary into fluid of a different density. In dam reservoirs, density currents are the main transport mechanism for the incoming sediments and they play an important role in redistribution of existing sediments. This paper aims to investigate velocity structure in the body of density currents. To this end, laboratory experiments were performed on density currents having various initial conditions and bottom slopes. Then, vertical velocity profiles were recorded in the body of density currents. The velocity structure of the currents was investigated by fitting equations to the wall and jet regions of the measured profiles, and the constants of the equations were yielded with R2 more than 0.80. Temporal and spatial evolution of density currents were also analysed to study the dynamics of the frontal region of the currents. It was observed that the currents having more bottom slope travel at a further distance. It was also found that 400% increase in the initial concentration of the currents can increase their frontal velocity up to 97%.References
Marino, B., Thomas, L.and Linden, P. 2005. The Front Condition for Gravity Currents. Journal of Fluid Mechanics. 536: 49-78.
Simpson, J.E. 1999. Gravity Currents: In the Environment and the Laboratory: Cambridge University Press.
Nasrollahpour, R. and Ghomeshi, M. 2012. Effect of Roughness Geometry on Characteristics of Density Currents Head. Indian Journal of Science and Technology. 5(12): 3783-3787.
Chowdhury, R.A. 2013. Effect of Roughness on Density Currents, in Department of Mechanical Engineering, The University Of Texas at San Antonio.
Adduce, C., Lombardi, V., Sciortino, G.and Morganti, M. 2009. Roughness Effects on Gravity Currents Dynamics. The Proceedings of the 33rd IAHR Congress, Canada.
Bühler, J., Oehy, C.and Schleiss, A. 2012. Jets Opposing Turbidity Currents and Open Channel Flows. Journal of Hydraulic Engineering. 139(1): 55-59.
Oehy, C.D., De Cesare, G.and Schleiss, A.J. 2010. Effect of Inclined Jet Screen on Turbidity Current. Journal of Hydraulic Research. 48(1): 81-90.
[8] Oehy, C.D. and Schleiss, A.J. 2007. Control of Turbidity Currents in Reservoirs by Solid and Permeable Obstacles. Journal of Hydraulic Engineering. 133(6): 637-648.
Kostic, S. and Parker, G. 2003. Progradational Sand-Mud Deltas in Lakes and Reservoirs. Part 1. Theory and Numerical Modeling. Journal of Hydraulic Research. 41(2): 127-140.
Nasrollahpour, R., Jamal, M.H., Ismail, Z., Ghomeshi, M.and Roushenas, P. 2015. The Influence of Roughness on the Propagation of Density Currents. Malaysian Journal of Civil Engineering. 27(Special Issue 2): 266-272.
Jiahua, F. 1986. Turbid Density Currents in Reservoirs. Water International. 11(3): 107-116.
Fan, J. and Morris, G.L. 1992. Reservoir Sedimentation. Ii: Reservoir Desiltation and Long-Term Storage Capacity. Journal of Hydraulic Engineering. 118(3): 370-384.
Cesare, G.D., Schleiss, A.and Hermann, F. 2001. Impact of Turbidity Currents on Reservoir Sedimentation. Journal of Hydraulic Engineering. 127(1): 6-16.
Sequeiros, O.E., Naruse, H., Endo, N., Garcia, M.H.and Parker, G. 2009. Experimental Study on Selfâ€Accelerating Turbidity Currents. Journal of Geophysical Research: Oceans (1978–2012). 114(C5).
De Cesare, G., Oehy, C.and Schleiss, A. 2008. Experiments on Turbidity Currents Influenced by Solid and Permeable Obstacles and Water Jet Screens. 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.
Ghomeshi, M. 1995. Reservoir Sedimentation Modelling.
Ellison, T. and Turner, J. 1959. Turbulent Entrainment in Stratified Flows. Journal of Fluid Mechanics. 6(03): 423-448.
Altinakar, M., Graf, W.and Hopfinger, E. 1996. Flow Structure in Turbidity Currents. Journal of Hydraulic Research. 34(5): 713-718.
Nasrollahpour, R., Ghomeshi, M.and Ahadiyan, J. 2012. Turbidity Currents Head Motion over Artificially Roughened Beds. World Applied Sciences Journal 19(9): 1278-1283.
Fragoso, A., Patterson, M.and Wettlaufer, J. 2013. Mixing in Gravity Currents. Journal of Fluid Mechanics. 734: R2.
Nasrollahpour, R., Jamal, M.H., Ghomesi, M., Ismail, Z.and Roushenas, P. 2015. Density Currents Dynamics over Rough Beds. Applied Mechanics and Materials. Trans Tech Publ.
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