Breakup of a Fluid Thread in a Confined Geometry: Droplet-Plug Transition Perturbation Sensitivity and Kinetic Stabilization With Confinement

Published

July 5, 2006

Author(s)

John G. Hagedorn, N S. Martys, J F. Douglas

Abstract

We investigate the influence of geometrical confinement on the breakup of long fluid threads in the absence of imposed flow using a Lattice Boltzmann model.  Our simulations primarily focus on the case of threads centered coaxially in a tube filled with another Newtonian fluid and subjected to both impulsive and random perturbations.  We observe a glass-like slowing down of the rate of thread breakup ( kinetic stabilization ) over a wide range of the confinement, 2.5 {less then or equal to} equivalent conductivity (= R_tube/R_thread) (less then or equal to) 10 and find that the relative surface energies of the liquid components influence this effect.  For equivalent conductivity < 2.3, there is a transition in the late-stage morphology between spherical droplets and tube plugs .  Unstable distorted droplets ( capsules ) form as transient structures for intermediate confinement (equivalent conductivity) {nearly equal to} 2.1).  The thread breakup process for more highly confined threads (equivalent conductivity {less then or equal to} 1.9) is sensitive to the nature of the initial thread perturbation.  Impulsive perturbations led to a bulging of the fluid near the tube wall, followed by thread breakup through the propagation of wave-like disturbances ( end-pinch instability ) initiating from thread rupture points that nucleate from the thread bulges.  Random impulses along the thread modeling thermal fluctuations, led to a complex breakup process involving a competition between the capillary wave and end-pinch instabilities.  We also briefly compare our simulations to threads confined between parallel plates and to multiple interacting threads under confinement.

Citation

Physical Review E (Statistical, Nonlinear, and Soft Matter Physics)

Volume

69

Pub Type

Journals

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Citation

Hagedorn, J. , Martys, N. and Douglas, J. (2006), Breakup of a Fluid Thread in a Confined Geometry: Droplet-Plug Transition Perturbation Sensitivity and Kinetic Stabilization With Confinement, Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50688 (Accessed April 24, 2024)