Experimental Investigation on Rising of a Sequence of Drops in a Viscous Fluid

Author

Abstract

Motion and deformation of a sequence of drops rising through an immiscible viscous fluid (water) were studied experimentally using an image analysis method. In order to have a complete investigation between the behavior of a drop moving in the wake region of another one and a single drop moving freely in a quiescent fluid, we compared the shape evolution and the drag coefficient related to a single drop and a distinct drop in a sequence. Also, the effect of non-Newtonian characteristics on the size variation and motion of drops was studied. Results show that addition of viscoelastic characteristics to a fluid causes a more stable shape in the drop and its deformation is closer to a single drop during motion in the wake region. Besides, in order to find a reasonable correlation between drag coefficient and Reynolds number for a drop moving in sequence, we used a two dimensional model based on drop trajectory. In addition, a theoretical correlation in the form was proposed by neglecting the effect of size variations of a single drop and it caused an error lower than 25% in comparison to real values. Comparison between drag coefficients of a single drop and a sequence of drops revealeddrops experience higher values of drag coefficient during the motion in sequence.

Keywords

References

[1] Fakhari A, Rahimian MH (2011) Investigation of deformation and breakup of a falling droplet using a multiple–relaxation-time lattice Boltzmann method. Comput Fluids. 40: 156–171.
[2] Wegener M, Kraume M, Paschedag A (2010) Terminal and transient drop rise velocity of single toluene droplets in water. AIChE J. 56(1): 2–10.
[3] Kushner J, Rother MA, Davis RH (2001) Buoyancy–driven interactions of viscous drops with deforming interfaces. J Fluid Mech. 446: 253–269.
[4] Brazier-Smith PR, Jennings SG, Latham J (1972) The interaction of falling water drops: coalescence. Proc R Soc London. 326: 393–408.
[5] Al–Matroushi E, Borhan A (2009) Coalescence of drops and bubbles rising through a non–Newtonian fluid in a tube. Interdisciplinary Transport Phenomena, 1161: 225–233.
[6] Ramaswamy S, Leal LG (1999) The deformation of a viscoelastic drop subjected to steady uniaxial extensional flow of a Newtonian fluid. J Non-Newtonian Fluid Mech. 85(2–3): 127–163.
[7] Wanchoo RK, Sharma SK, Gupta R (2003) Shape of Newtonian liquid drop moving through an immiscible quiescent non-Newtonian liquid. Chem Eng Process. 42(5): 387–393.
[8] Sostarecz MC, Belmonte A (2003) Motion and shape of a viscoelastic drop falling through a viscous fluid. J Fluid Mech. 497: 235–252.
[9] Acharya A, Ulbrecht J (1978) Note on the influence of viscoelasticity on coalescence rate of bubble and drops. AIChE J. 24: 348–351.
[10] Hetsroni G, Haber S (1978) Low Reynolds number motion of two drops submerged in an unbounded arbitrary velocity field. Int J Multiphase Flow. 4(1): 1–17.
[11] Davis RH (1999) Buoyancy-driven viscous interaction of a rising drop with a smaller trailing drop. Phys Fluids 11: 1016–1028.
[12] Hugli H, Gonzalez J (2000) Drop volume measurement by vision. SPIE 3966–11: 60–66.
[13] Moremedi GM, Mason DP (2010) Streamlines and detached wakes in steady flow past a spherical liquid drop. Mathematical and Computational Application, 15(4): 543–557.
[14] Munson BR, Young DF, Okishi TH (2009) Fundamentals of fluid mechanics, 6th Ed., John–Wiley.
[15] Igarashi T, Terachi N (2002) Drag reduction of flat plate normal to airstream by flow control using a rod. J Wind Eng Ind Aerod. 90: 359–376.
Journal of Solid and Fluid Mechanics
Volume 1, Issue 1 - Serial Number 1
September and October 2011
Pages 39-46

Files

Share

How to cite

Statistics