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Full-Text Articles in Physics
Structure And Dynamics Of Self-Assembling Colloidal Monolayers In Oscillating Magnetic Fields, Alison E. Patteson (Koser), Nathan C. Keim, Paulo E. Arratia
Structure And Dynamics Of Self-Assembling Colloidal Monolayers In Oscillating Magnetic Fields, Alison E. Patteson (Koser), Nathan C. Keim, Paulo E. Arratia
Physics - All Scholarship
Many fascinating phenomena such as large-scale collective flows, enhanced fluid mixing, and pattern formation have been observed in so-called active fluids, which are composed of particles that can absorb energy and dissipate it into the fluid medium. For active particles immersed in liquids, fluid-mediated viscous stresses can play an important role on the emergence of collective behavior. Here, we experimentally investigate their role in the dynamics of self-assembling magnetically driven colloidal particles which can rapidly form organized hexagonal structures. We find that viscous stresses reduce hexagonal ordering, generate smaller clusters, and significantly decrease the rate of cluster formation, all while …
Measuring Material Relaxation And Creep Recovery In A Microfluidic Device, Alison E. Patteson (Koser), Lichao Pan, Nathan C. Keim, Paulo E. Arratia
Measuring Material Relaxation And Creep Recovery In A Microfluidic Device, Alison E. Patteson (Koser), Lichao Pan, Nathan C. Keim, Paulo E. Arratia
Physics - All Scholarship
We present a novel method of testing creep recovery in a microfluidic device. This method allows for the measurement of relaxation time of fluids at low strain. After applying a steady pressure-driven flow along a microchannel, the pressure is released and the fluid is allowed to relax and come to rest. Local strains are observed via the time-dependent velocity profiles and are fit to a general viscoelastic model to obtain the fluids' relaxation times. The use of polymeric solutions of various molecular weights allows for the observation of time scales for strains ranging from 0.01 to 10. Results are consistent …
Multiple Transient Memories In Sheared Suspensions: Robustness, Structure, And Routes To Plasticity, Nathan C. Keim, Joseph D. Paulsen, Sidney R. Nagel
Multiple Transient Memories In Sheared Suspensions: Robustness, Structure, And Routes To Plasticity, Nathan C. Keim, Joseph D. Paulsen, Sidney R. Nagel
Physics - All Scholarship
Multiple transient memories, originally discovered in charge-density-wave conductors, are a remarkable and initially counterintuitive example of how a system can store information about its driving. In this class of memories, a system can learn multiple driving inputs, nearly all of which are eventually forgotten despite their continual input. If sufficient noise is present, the system regains plasticity so that it can continue to learn new memories indefinitely. Recently, Keim and Nagel [Phys. Rev. Lett. 107, 010603 (2011)] showed how multiple transient memories could be generalized to a generic driven disordered system with noise, giving as an example simulations of a …
Approach And Coalescence Of Liquid Drops In Air, Joseph Paulsen
Approach And Coalescence Of Liquid Drops In Air, Joseph Paulsen
Physics - All Scholarship
The coalescence of liquid drops has conventionally been thought to have just two regimes when the drops are brought together slowly in vacuum or air: a viscous regime corresponding to the Stokes-flow limit and a later inertially dominated regime. Recent work found that the Stokes-flow limit cannot be reached in the early moments of coalescence, because the inertia of the drops cannot be neglected then. Instead, the drops are described by an "inertially limited viscous" regime, where surface tension, inertia, and viscous forces all balance. The dynamics continue in this regime until either viscosity or inertia dominate on their own. …