302 citations · 1.5k across the 32 of their papers we have counts for
8 papers · 1 filter
Undulatory swimming in shear-thinning fluids: Experiments with C. elegans
David A. Gagnon, Nathan C. Keim, Paulo E. Arratia
The swimming behaviour of microorganisms can be strongly influenced by the rheology of their fluid environment. In this manuscript, we experimentally investigate the effects of she…
Fluid-Induced Propulsion of Rigid Particles in Wormlike Micellar Solutions
David A. Gagnon, Nathan C. Keim, Xiaoning Shen +1
In the absence of inertia, a reciprocal swimmer achieves no net motion in a viscous Newtonian fluid. Here, we investigate the ability of a reciprocally actuated particle to transla…
The structure and dynamics of self-assembling colloidal monolayers in oscillating magnetic fields
Alison E. Koser, Nathan C. Keim, Paulo E. Arratia
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 pa…
Self-assembling paramagnetic colloids in oscillating magnetic fields
Alison E. Koser, Nathan C. Keim, Paulo E. Arratia
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 pa…
Dropping the Ball: The effect of anisotropic granular materials on ejecta and impact crater shape
Philip Drexler, Nathan Keim, Paulo Arratia
In this fluid dynamics video, we present an experimental investigation of the shape of impact craters in granular materials. Complex crater shapes, including polygons, have been ob…
Vibration and Nonlinear Resonance in the Break-up of an Underwater Bubble
Lipeng Lai, Nathan C. Keim, Kamel Fezzaa +2
We use high-speed X-ray phase-contrast imaging, weakly nonlinear analysis and boundary integral simulations to characterize the final stage of underwater bubble break-up. The X-ray…
Fluid Elasticity Can Enable Propulsion at Low Reynolds Number
Nathan C. Keim, Mike Garcia, Paulo E. Arratia
Conventionally, a microscopic particle that performs a reciprocal stroke cannot move through its environment. This is because at small scales, the response of simple Newtonian flui…
Perturbed breakup of gas bubbles in water: Memory, gas flow, and coalescence
Nathan C. Keim
The pinch-off of an air bubble from an underwater nozzle ends in a singularity with a remarkable sensitivity to a variety of perturbations. I report on experiments that break both…