School of Mechanical Engineering Seminar
Monday April 24.04.2023 at 14:00
Wolfson Building of Mechanical Engineering, Room 206
Viscoelastic flows in slowly varying geometries
Evgeniy Boyko
Assistant Professor of Mechanical Engineering
Technion – Israel Institute of Technology
Email: evgboyko@technion.ac.il
Pressure-driven flows of viscoelastic in narrow non-uniform geometries are ubiquitous in nature and various technological applications. The complex rheological behavior of non-Newtonian fluids affects their hydrodynamic features, including the flow rate–pressure drop relation. Despite many measurements and simulations of the flow rate–pressure drop relation of various complex fluids in different geometries, the understanding of how viscoelasticity modifies this relation remains poorly understood. Furthermore, in some cases, numerical simulations not only fail to quantitatively capture the experiments, but even qualitatively contradict them.
In this talk, I will discuss the flow rate–pressure drop relation of viscoelastic fluids in non-uniform geometries and present the long-standing contradiction between experiments and simulations. While experiments show the increase in the flow resistance, defined as the ratio of the pressure drop to the flow rate, simulations predict its decrease.
Aiming to understand the cause of this contradiction, I will present a theoretical framework for calculating the flow rate–pressure drop relation of viscoelastic fluids in arbitrarily shaped, narrow geometries. I will show that for the Oldroyd-B constitutive model, which is the most used continuum model for viscoelastic fluids derivable from microscopic principles, our theoretical predictions are in excellent agreement with simulations. However, our analytical results using the Oldroyd-B model still fail to rationalize the increase in the flow resistance observed experimentally. I will discuss the shortcomings of the Oldroyd-B model, which may lead to this disagreement, and their resolution through incorporating additional microscopic features of polymers.
Finally, I will briefly discuss additional research directions our group is pursuing and the long-term vision of bridging the gap between fluid mechanics and polymer science.
Evgeniy Boyko is an Assistant Professor of Mechanical Engineering at Technion – Israel Institute of Technology. He is equally interested in understanding basic physical mechanisms related to fluid mechanics of non-Newtonian fluids and in leveraging them to improve existing applications and create new technologies using complex fluids. Evgeniy earned his B.Sc. (2015) and Ph.D. (direct track) (2020) from the Faculty of Mechanical Engineering at Technion. He worked as a postdoctoral research fellow at the Schools of Mechanical and Chemical Engineering at Purdue University in 2021-2022 and was a postdoctoral research fellow at Princeton University in 2020-2021. He received the Adams Fellowship for Ph.D. studies, the Jacobs Publication Award, and the Rothschild, Zuckerman, Blavatnik, and Gilbreth Fellowships for postdoctoral studies.
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