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Full-Text Articles in Physical Sciences and Mathematics
Paraboloidal Crystals, Mark Bowick, Luca Giomi
Paraboloidal Crystals, Mark Bowick, Luca Giomi
Physics - All Scholarship
The interplay between order and geometry in soft condensed matter systems is an active field with many striking results and even more open problems. Ordered structures on curved surfaces appear in multi-electron helium bubbles, viral and bacteriophage protein capsids, colloidal self-assembly at interfaces and in physical membranes. Spatial curvature can lead to novel ground state configurations featuring arrays of topological defects that would be excited states in planar systems. We illustrate this with a sequence of images showing the Voronoi lattice (in gold) and the corresponding Delaunay triangulations (in green) for ten low energy configurations of a system of classical …
Sheared Active Fluids: Thickening, Thinning And Vanishing Viscosity, Luca Giomi, Tanniemola B. Liverpool, M. Cristina Marchetti
Sheared Active Fluids: Thickening, Thinning And Vanishing Viscosity, Luca Giomi, Tanniemola B. Liverpool, M. Cristina Marchetti
Physics - All Scholarship
We analyze the behavior of a suspension of active polar particles under shear. In the absence of external forces, orientationally ordered active particles are known to exhibit a transition to a state of non-uniform polarization and spontaneous flow. Such a transition results from the interplay between elastic stresses, due to the liquid crystallinity of the suspension, and internal active stresses. In the presence of an external shear we find an extremely rich variety of phenomena, including an effective reduction (increase) in the apparent viscosity depending on the nature of the active stresses and the flow-alignment property of the particles, as …