Selective withdrawal of polymer solutions: Experiments |
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| Authors: | Diwen Zhou James J Feng |
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| Institution: | 1. Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC V6T 1Z3, Canada;2. Department of Mathematics, University of British Columbia, Vancouver, BC V6T 1Z2, Canada;1. Rheology Research Center, University of Wisconsin-Madison, Madison, WI 53706, United States;2. Mechanical Engineering Department, University of Wisconsin-Madison, Madison, WI 53706, United States;3. Chemical and Biological Engineering Department, University of Wisconsin-Madison, Madison, WI 53706, United States;4. Chemical Engineering Department, Queen’s University, Kingston, ON K7L 3N6, Canada;5. Polymers Research Group, Queen’s University, Kingston, ON K7L 3N6, Canada;1. Oxford Centre for Collaborative Applied Mathematics, Mathematical Institute, The University of Oxford, OX1 3LB, United Kingdom;2. Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL 60208, United States;3. Mechanical Science and Engineering, University of Illinois, Urbana-Champaign, IL, United States;1. College of Science, Nanjing Agricultural University, Nanjing 210095, PR China;2. Department of Mathematics and Information Technology, The Hong Kong Institute of Education, 10 Po Ling Road, Tai Po, New Territories, Hong Kong |
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| Abstract: | Selective withdrawal refers to the process of drawing one or both components of stratified fluids through a tube placed near their interface. This paper reports an experimental study of selective withdrawal of viscous and viscoelastic liquids under air. The key mechanism of interest is how the viscoelasticity in the bulk liquid affects the evolution of the free surface. This is investigated by comparing the interfacial behavior between a Newtonian silicone oil and two dilute polymer solutions. While the surface undergoes smooth and gradual deformation for Newtonian liquids, for the polymer solutions there is a critical transition where the surface forms a cusp from which an air jet emanates toward the suction tube. This transition shows a hysteresis when the flow rate or location of the tube is varied. In the subcritical state, the surface of polymer solutions deform much more than its Newtonian counterpart but the deformation is more localized. The interfacial behavior of the polymer solutions can be attributed to the large polymer stress that develops under the surface because of predominantly extensional deformation. |
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