Eric S.G. Shaqfeh

Eric S.G. Shaqfeh

2011 Bingham Medalist

Stanford University

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Eric S. G. Shaqfeh received his B.S.E. degree in chemical engineering in 1981 from Princeton University (summa cum laude) and an M.S. (1982) and Ph.D. (1986) from Stanford University, where his dissertation research on buoyancy-driven convective flow was supervised by Andy Acrivos. Following a postdoctoral year at the University of Cambridge working with G. K. Batchelor and E. J. Hinch, Eric joined AT&T Bell Laboratories (Murray Hill, NJ USA) as a member of technical staff in 1987. Eric moved to academia in 1990 joining the faculty at Stanford University and rising to full professor in 1999. Among various awards Eric has received the NSF Presidential Young Investigator award (1990), the Camille and Henry Dreyfus Teacher-Scholar Award (1994), and the ASEE Curtix W. McGraw Research Award (1998), as well as numerous honorary lectureship positions. Eric is a fellow of the American Physical Society, associate editor of Physics of Fluids, and on the editorial board of three other journals.

When Eric began his research career at AT&T Bell Laboratories, his research was in theoretical fluid mechanics and suspension mechanics. Since that time, the scope of his research interests has steadily expanded, first to combined experimental and theoretical suspension rheology, then to viscoelastic fluid mechanics and stability theory, to the dynamics of dilute flexible polymers, and now to entangled polymer dynamics, polymer turbulent drag reduction, polymer biophysics, and even blood rheology.

Eric is particularly well known to the rheological community for his body of theories of transport in suspensions of rods, including non-local interactions. This work was responsible to a significant degree for his being awarded the Frenkiel Award of the American Physical Society for research in fluid mechanics by a young researcher. A particularly important contribution in this area is Eric’s analysis, with Glenn Fredrickson, of hydrodynamic interactions in fiber suspensions using slender body theory. This work marked a milestone of rigor in this important area, extending the work of Batchelor, and allowing for calculation of effective rotational diffusivities in non-Brownian suspensions resulting from multi-body hydrodynamic interactions. He and his group also produced a beautiful theory, with supporting experiexperiments, on stochastic dynamics of flow through a fixed bed, including the effects on polymer dynamics of such flows. Eric has continued his work on suspension dynamics up to the present, with his recent studies of sedimentation dynamics of colloids, and his rigorous treatment, with Jason Butler, of the hydrodynamics of beadrod chains.

While still at Bell Labs, Eric began writing a series of papers on dynamics and fluid mechanics of dilute polymer solutions. His work in these areas began with a collaborative study of purely elastic instabilities in polymeric fluids, including work co-authored with Susan Muller and Ron Larson on the Taylor-Couette instability, and continued in his own group with analyses of purely elastic instabilities in the Taylor-Dean flow, eccentric cylinder flow, and continuing with analysis of the effects of inertia. He also produced the most significant body of work world-wide on Brownian dynamics simulations of flexible polymers, eventually collaborating with Steve Chu to perform wonderfully elegant and important experiments on long DNA molecules in various flows, including extensional, shear, and mixed flows. In an experimental tour de force, Eric and coworkers were able to create a mixed flow in which real-time microscopic observation of a single stained DNA molecule could be achieved. This work showed the transitions between polymer stretching and tumbling present in such flows, and, when combined with Brownian dynamics simulations, provided an essentially complete experimental and theoretical understanding of the molecular dynamics of dilute flexible polymers in general velocity gradients. Even more spectacular was Eric’s work with Steve Chu on extensional flows of super-long (1 mm long) DNA molecules. These studies confirmed the prediction made long ago by de Gennes that long polymers should show quasi-hysteresis in plots of chain stretch versus extension rate. That is, there should be two quasi steady-state values of polymer stretch at each value of extension rate, for a range of extension rates near the critical value for a “coil-stretch transition.” This prediction has beautiful analogies to phase co-existence in thermodynamics, where the coiled and stretched states are the two “coexisting phases,” and there are “nucleation” events required to transit from one state to the other. Not only did Eric and his colleagues finally perform the definitive experiment on this topic (published in Science), but Eric’s group followed this up with a comprehensive theoretical and computational analysis that included predictions of magnitude of the hysteresis, the time scales required for barrier hopping between coiled and stretched states, and the development of computationally cheap coarse-grained dumbbell models that capture the behavior of the much more sophisticated fine-grained models. This body of work, on its own, qualifies Eric as one of the pre-eminent molecular rheologists in the world.

Another very important rheological contribution by Eric Shaqfeh is the development of a greatly enhanced understanding of the mechanisms of polymer drag reduction. In this work, Eric’s group carried out direct numerical simulation (DNS) of turbulent flows of viscoelastic fluids and determined the structures of drag-reduced turbulence for both flexible and rigid polymers and particles. In some of the most comprehensive and insightful DNS studies of full turbulence yet, Eric developed insights into the differences between modest and maximal drag reduction and the importance of biaxial extensional velocity gradients in the drag-reduction mechanism.

Eric has recently developed a powerful experimental program in the area of dynamics of entangled flexible polymers, again using stained DNA molecules and elegant flow geometries to directly visualize the relevant polymer dynamics. In his earliest work, he discovered, among other things, a new relaxation time in the relaxation dynamics of entangled polymers under flow, which was apparently not anticipated in any existing theory in this field. Very recently, Eric and his group have used so-called “slip link” simulations to explain one of the major mysteries of extensional rheology of entangled polymers, namely the -1/2 power-law extension-thinning regime seen at extension rates above the inverse reptation time by Ole Hassager and coworkers. Eric’s work indicates that this regime results from flow-induced disentanglement of polymer chains, an idea much discussed, but never convincingly demonstrated theoretically or computationally. This break-through illustrates the speed with which Eric is able to move to the forefront of a deep, well-studied, and complex area.

Eric’s recent computational work is on margination of platelets in circulating blood flow. Eric’s group is using advanced computational methods to track red blood cells under flow through a capillary, including their shape deformations, their hydrodynamic interactions, their migration across the capillary, and their effect on other blood components, specifically platelets. These remarkable simulations have set a new standard in computational rheology, demonstrating that rigorous simulations are now possible even for fluids as complex as blood. Eric’s findings correlate well with experimental data and provide deep insights into platelet transport, with implications for wound healing.

As should be evident from the above account, not only is Eric a deeply insightful researcher, but also an excellent and valued collaborator. Outside of research, Eric is also an excellent organizer and manager. He emerged as the leader of the Stanford team in the DARPA-sponsored drag reduction research program, managing 5-10 faculty and students in a complex project involving experiments and simulations of phenomena ranging in scale from molecular to ocean-going vessels.

Eric is a devoted family man, sharing his life with his wife Terhilda Garrido and their children Stefan and Elena. The family enjoys traveling together, having recently taken family trips to Peru, Mexico, Death Valley California, and Greece. Eric has a broad range of nonscientific interests and talents including chess, skiing, golf, and racquetball. Finally, Eric enjoys cooking and good wine, as well as a good joke even when he is the butt of it, often skewering himself with relish. A gathering with Eric is a sure opportunity for fun. A sincere and hearty congratulations to Eric on receiving the Bingham medal this year.