Irmgard Bischofsberger - Instabilities and flow-induced defects in lyotropic chromonic liquid crystals
|24 March 2021
|14:00 - 15:00
|What is it:
|Department of Mathematics
|Who is it for:
|University staff, External researchers, Current University students
Irmgard Bischofsberger (MIT) joins us for this virtual seminar in the Physical Applied Mathematics Series
This seminar will be held via Zoom. Please email firstname.lastname@example.org if you require the meeting details.
Lyotropic chromonic liquid crystals in the nematic phase are anisotropic fluids. We exploit this intrinsic anisotropy to probe growth morphology transitions that occur in the viscous-fingering instability upon the displacement of the liquid crystal by a less-viscous Newtonian liquid. In isotropic systems, this instability produces complex patterns that are characterized by repeated branching of the evolving structure, which leads to the common morphologies of fractal or dense-branching growth. In anisotropic systems, by contrast, the growth morphology changes to dendritic growth characterized by stable needle-like structures. We show that the morphology transition coincides with the onset of shear-alignment at high shear rates, where the shear forces become dominant over the elastic forces from the nematogenic potential. Below this critical shear rate, the lyotropic chromonic liquid crystal exhibits a tumbling behavior that leads to the formation of pure twist disclination loops and, surprisingly, to the spontaneous emergence of chiral domains at low shear rates.
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