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Breakage of a drop of inviscid fluid due to a pressure fluctuation at its surface

Shreekumar, * and Kumar, R and Gandhi, KS (1996) Breakage of a drop of inviscid fluid due to a pressure fluctuation at its surface. In: Journal of Fluid Mechanics, 328 . pp. 1-17.

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Abstract

In this work, an attempt is made to gain a better understanding of the breakage of low-viscosity drops in turbulent flows by determining the dynamics of deformation of an inviscid drop in response to a pressure variation acting on the drop surface. Known scaling relationships between wavenumbers and frequencies, and between pressure fluctuations and velocity fluctuations in the inertial subrange are used in characterizing the pressure fluctuation. The existence of a maximum stable drop diameter d(max) follows once scaling laws of turbulent flow are used to correlate the magnitude of the disruptive forces with the duration for which they act. Two undetermined dimensionless quantities, both of order unity, appear in the equations of continuity, motion, and the boundary conditions in terms of pressure fluctuations applied on the surface. One is a constant of proportionality relating root-mean-square values of pressure and velocity differences between two points separated by a distance l. The other is a Weber number based on turbulent stresses acting on the drop and the resisting stresses in the drop due to interfacial tension. The former is set equal to 1, and the latter is determined by studying the interaction of a drop of diameter equal to d(max) with a pressure fluctuation of length scale equal to the drop diameter. The model is then used to study the breakage of drops of diameter greater than d(max) and those with densities different from that of the suspending fluid. It is found that, at least during breakage of a drop of diameter greater than d(max) by interaction with a fluctuation of equal length scale, a satellite drop is always formed between two larger drops. When very large drops are broken by smaller-length-scale fluctuations, highly deformed shapes are produced suggesting the possibility of further fragmentation due to instabilities. The model predicts that as the dispersed-phase density increases, d(max) decreases.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Cambridge university press.
Department/Centre: Division of Mechanical Sciences > Chemical Engineering
Date Deposited: 04 Aug 2011 05:42
Last Modified: 04 Aug 2011 05:42
URI: http://eprints.iisc.ernet.in/id/eprint/37055

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