Breakage of viscoelastic drops in turbulent stirred dispersions

Koshy, Abraham and Das, TR and Kumar, R and Gandhi, KS (1988) Breakage of viscoelastic drops in turbulent stirred dispersions. In: Chemical Engineering Science, 43 (10). pp. 2625-2631.

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Abstract

The existing models of drop breakage in stirred turbulent dispersions are applicable only to purely viscous dispersed phases. In their present form, they are found to underpredict the diameters of the largest stable drops formed when a viscoelastic fluid is dispersed into a Newtonian liquid. In purely viscous fluids, the turbulent stresses are opposed both by the stresses due to interfacial tension and the viscous stresses generated as the drop deforms. In viscoelastic fluids, drop deformation produces additional retractive elastic stresses which also oppose turbulent stresses. As the deformation rates are large, the retractive stresses can be large in magnitude. Assuming that these additional stresses decay with time, a model of viscoelastic drop breakage in turbulent stirred dispersions has been developed. The new model quantitatively predicts the dmax of viscoelastic fluids. The model, however, does not predict the observation that when the time constant of the fluid becomes large (λ > 0.5 s), the fluid can not be dispersed into droplets up to agitator speeds of about 10 rps in our equipment.

Item Type:	Journal Article
Publication:	Chemical Engineering Science
Publisher:	Elsevier Science
Additional Information:	Copyrights of this article belongs to Elsevier Science.
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering
Date Deposited:	29 Jul 2009 03:11
Last Modified:	19 Sep 2010 05:39
URI:	http://eprints.iisc.ac.in/id/eprint/21860

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