Hostname: page-component-7c8c6479df-5xszh Total loading time: 0 Render date: 2024-03-28T09:45:23.722Z Has data issue: false hasContentIssue false

Viscoelastic effects on drop deformation in steady shear

Published online by Cambridge University Press:  27 September 2005

PENGTAO YUE
Affiliation:
Department of Chemical and Biological Engineering and Department of Mathematics, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
JAMES J. FENG
Affiliation:
Department of Chemical and Biological Engineering and Department of Mathematics, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
CHUN LIU
Affiliation:
Department of Mathematics, The Pennsylvania State University, University Park, PA 16802, USA
JIE SHEN
Affiliation:
Department of Mathematics, Purdue University, West Lafayette, IN 47907, USA

Abstract

This paper applies a diffuse-interface model to simulate the deformation of single drops in steady shear flows when one of the components is viscoelastic, represented by an Oldroyd-B model. In Newtonian fluids, drop deformation is dominated by the competition between interfacial tension and viscous forces due to flow. A fundamental question is how viscoelasticity in the drop or matrix phase influences drop deformation in shear. To answer this question, one has to deal with the dual complexity of non- Newtonian rheology and interfacial dynamics. Recently, we developed a diffuse-inter-face formulation that incorporates complex rheology and interfacial dynamics in a unified framework. Using a two-dimensional spectral implementation, our simulations show that, in agreement with observations, a viscoelastic drop deforms less than a comparable Newtonian drop. When the matrix is viscoelastic, however, the drop deformation is suppressed when the Deborah number $De$ is small, but increases with $De$ for larger $De$. This non-monotonic dependence on matrix viscoelasticity resolves an apparent contradiction in previous experiments. By analysing the flow and stress fields near the interface, we trace the effects to the normal stress in the viscoelastic phase and its modification of the flow field. These results, along with prior experimental observations, form a coherent picture of viscoelastic effects on steady-state drop deformation in shear.

Type
Papers
Copyright
© 2005 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)