Article ID Journal Published Year Pages File Type
671034 Journal of Non-Newtonian Fluid Mechanics 2011 12 Pages PDF
Abstract

The effect of an insoluble surfactant on the flow instability of two upper convected Maxwell (UCM) fluid co-extrusion flow in a circular pipe is studied using a linear normal-mode and complementary energy analysis. The influences of surfactant and fluid elasticity on the interfacial instability at low Reynolds number (ℝ→0)(ℝ→0) are of principal concern. The results show that the interfacial perturbation flow, which is induced due to elasticity stratification, can drain the surfactant from the interfacial wave trough and push it toward the crest. Thereby, the interplay of the elasticity stratification and the surfactant acts to stabilize the capillary instability. The neutral curve in the Weissenberg number (We)–axial wavenumber (k  ) plane is presented. A window of parameters is identified in which the flow is linearly stable. As the radius of the cylinder tends to infinity, a viscoelastic thread suspended in a quiescent infinite ambient fluid is obtained. Corresponding results show that the influence of fluid elasticity on flow instability is weakened with the increasing of Reynolds number (ℝ)(ℝ). Similar results can also be received for the influence of surfactant.

Related Topics
Physical Sciences and Engineering Chemical Engineering Fluid Flow and Transfer Processes
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