High-speed tomographic PIV was used to investigate the coalescence of drops placed on a liquid/liquid interface; the coalescence of a single drop and of a drop in the presence of an adjacent drop (side-by-side drops) was investigated. The viscosity ratio between the drop and surrounding fluids was 0.14, the Ohnesorge number (Oh = μd/(ρdσD)1/2) was 0.011, and Bond numbers (Bo = (ρ d − ρ s )gD 2/σ) were 3.1–7.5. Evolving volumetric velocity fields of the full coalescence process allowed for quantification of the velocity scales occurring over different time scales. For both single and side-by-side drops, the coalescence initiates with an off-axis film rupture and film retraction speeds an order of magnitude larger than the collapse speed of the drop fluid. This is followed by the formation and propagation of an outward surface wave along the coalescing interface with wavelength of approximately 2D. For side-by-side drops, the collapse of the first drop is asymmetric due to the presence of the second drop and associated interface deformation. Overall, tomographic PIV provides insight into the flow physics and inherent three-dimensionalities in the coalescence process that would not be achievable with flow visualization or planar PIV only.
This is a preview of subscription content, log in to check access.
Buy single article
Instant unlimited access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
In all results, t = 0 corresponds with the initial film rupture.
Blanchette F, Bigioni TP (2006) Partial coalescence of drops at liquid interfaces. Nat Phys 2:254
Burrill KA, Woods DR (1973) Film shapes for deformable drops at liquid-liquid interfaces. J Colloid Interface Sci 42(1)
Charles GE, Mason SG (1960) The mechanism of partial coalescence of liquid drops at liquid/liquid interfaces. J Colloid Sci 15:105
Chen X, Mandre S, Feng JJ (2006) Partial coalescence between a drop and a liquid-liquid interface. Phys Fluids 18:051705
Chi BK, Leal LG (1989) A theoretical study of the motion of a viscous drop toward a fluid interface at low Reynolds number. J Fluid Mech 201:123
Cresswell RW, Morton BR (1995) Drop-formed vortex rings—the generation of vorticity. Phys Fluids 7:1363
Elsinga GE, Scarano F, Wieneke B, van Oudheusden BW (2006) Tomographic particle image velocimetry. Exp Fluids 41:933–947
Geller AW, Lee SH, Leal LG (1986) The creeping motion of a spherical particle toward a deformable interface. J Fluid Mech 169:27
Hartland S (1967) The coalescence of a liquid drop at a liquid-liquid interface. Part II: film thickness. Trans Inst Chem Eng 45:T102
Lamb H (1932) Hydrodynamics, 6th edn. Cambridge University Press, Cambridge
Liow J-L (2001) Splash formation by spherical drops. J Fluid Mech 427:73–105
Mohamed-Kassim Z, Longmire EK (2004) Drop coalescence through a liquid/liquid interface. Phys Fluids 16:2170
Thoroddsen ST, Takehara K (2000) The coalescence cascade of a drop. Phys Fluids 12:1265
Thoroddsen ST, Etoh TG, Takehara K (2008) High-speed imaging of drops and bubbles. Annu Rev Fluid Mech 40:257–285
Wieneke B (2007) Volume self-calibration for stereo-PIV and tomographic-PIV, 7th International Symposium on Particle Image Velocimetry, Rome, Italy
Yue P, Zhou C, Feng JJ (2006) A computational study of the coalescence between a drop and an interface in Newtonian and viscoelastic fluids. Phys Fluids 18:102102
This work was supported by the American Chemical Society Petroleum Research Fund through Grant 42939-AC9 and the National Science Foundation through Grant CTS-0320327. The authors would like to thank Bernd Wieneke and Steve Anderson of LaVision, Inc for providing the Tomographic PIV software and for assistance with the experiments and processing.
About this article
Cite this article
Ortiz-Dueñas, C., Kim, J. & Longmire, E.K. Investigation of liquid–liquid drop coalescence using tomographic PIV. Exp Fluids 49, 111–129 (2010). https://doi.org/10.1007/s00348-009-0810-7
- Vortex Ring
- Viscosity Ratio
- Coalescence Process
- Drop Surface
- Film Rupture