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Measuring Material Microstructure Under Flow Using 1-2 Plane Flow-Small Angle Neutron Scattering
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Shear banding in nematogenic fluids with oscillating orientational dynamics
R Lugo-Frias1, H Reinken2, S H L Klapp2
1Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623, Berlin, Germany. lugo-frias@tu-berlin.de.
The European Physical Journal. E, Soft Matter
|September 28, 2016
Summary
This study reveals new shear-banded states in flowing liquid crystals, showing distinct dynamic regions. Shear banding appears with non-monotonic flow curves, particularly S-shaped ones in initially isotropic systems.
Area of Science:
- Fluid dynamics
- Soft matter physics
- Rheology
Background:
- Nematogenic fluids exhibit complex behavior under shear.
- Understanding shear banding is crucial for fluid dynamics and material science.
- Previous studies explored shear banding, but new dynamic regimes require investigation.
Purpose of the Study:
- To investigate shear banding in nematogenic fluids under planar Couette flow.
- To characterize new shear-banded states with oscillatory orientational dynamics.
- To analyze the influence of system parameters and boundary conditions on shear banding.
Main Methods:
- Mesoscopic dynamical equations for orientational order parameter and shear stress.
- Numerical calculations focusing on spatial variations in the shear gradient direction.
- Analysis of homogeneous system dynamics near isotropic-nematic transitions and in the nematic phase.
Main Results:
- Discovery of novel shear-banded states with regions of regular oscillatory orientational dynamics.
- Demonstration that shear banding is linked to non-monotonic flow curves in homogeneous systems.
- Observation of a typical S-shaped flow curve for initially isotropic systems exhibiting shear banding.
Conclusions:
- Shear banding in nematogenic fluids can lead to complex, spatially inhomogeneous states.
- The dynamics of shear banding are strongly influenced by the initial state (isotropic vs. nematic) and flow conditions.
- Further research into boundary conditions and correlation lengths can refine understanding of these phenomena.
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