It is well known that individual vesicles or liposomes (i.e., fluid enclosed by a lipid bilayer membrane suspended in a second fluid) are characterized by a remarkable dynamics in flow. For vesicles that are “near spheres” this dynamics includes at least 5 different types of orbits in shear flow that are functions of the viscosity ratio between the inner and outer fluid as well as the capillary number based on the bending modulus. However, this dynamics becomes even richer as the reduced volume falls below about 0.65 where now there are at least three equilibrium shapes (prolates, discocytes, and stomatocytes) which are linearly stable. It is therefore not surprising that a suspension of vesicles is characterized by fascinating collective behavior as well. I will discuss our recent development of a numerical code (based on Loop subdivision) which allows the Stokes flow simulation of non-dilute suspensions of vesicles and capsules at essentially any value of the reduced volume. We will then use these numerical simulations to examine a number of interesting phenomena including: 1) the lift of a vesicle away from a wall and the resulting “Fahraeus-Lindqvist” layer for the flow of a wall-bound suspension of vesicles, 2) the effective rheology and dynamics of a non-dilute vesicle suspension under shear, and 3) the stability of vesicle shapes in extensional flows.
About the Speaker
Eric Shaqfeh is the Lester Levi Carter Professor and Department Chair of Chemical Engineering at Stanford University. He earned a B.S.E. summa cum laude from Princeton University (1981), and a M.S. (1982) and Ph.D. (1986) from Stanford University, all in Chemical Engineering. In 1986, he was a NATO postdoctoral fellow at the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge. From 1987 through 1989 he was employed as a Member of Technical Staff at AT&T Bell Laboratories in Murray Hill, NJ before joining the Stanford Chemical Engineering faculty in early 1990. In 2001 he received a dual appointment and became Professor of Mechanical Engineering. He is most recently (as of 2004) a faculty member in the Institute of Computational and Mathematical Engineering at Stanford. Shaqfeh’s current research interests include non-Newtonian fluid mechanics (especially in the area of elastic instabilities, and turbulent drag reduction), nonequilibrium polymer statistical dynamics (focusing on single molecules studies of DNA), and suspension mechanics (particularly of fiber suspensions and particles/vesicles in microfluidics). He has authored or co-authored over 180 publications and has been an Associate Editor of the Physics of Fluids since 2006. Shaqfeh has received the APS Francois N. Frenkiel Award 1989, the NSF Presidential Young Investigator Award 1990, the David and Lucile Packard Fellowship in Science and Engineering 1991, the Camile and Henry Dreyfus Teacher--Scholar Award 1994, the W.M. Keck Foundation Engineering Teaching Excellence Award 1994, the 1998 ASEE Curtis W. McGraw Award, and the 2011 Bingham Medal from the Society of Rheology. A Fellow of the American Physical Society (2001) and a member of the National Academy of Engineering(2013), he has held a number of professional lectureships, most recently the Merck Distinguished Lectureship, Rutgers (2003), the Corrsin Lectureship, Johns Hopkins (2003) and the Katz Lectureship, CCNY (2004). He was also the Hougen Professor of Chemical Engineering at the University of Wisconsin (2004) and the Probstein Lecturer at MIT (2011).
*Times, dates and titles are subject to change. Check mechanical.illinois.edu for updated information. These seminars count toward the requirements for ME 590 and TAM 500.