Stress Driven Shear Bands and the Effect of Confinement on Their StructuresA Rheological, Flow Visualization, and Rheo-SALS Study

Langmuir ◽  
2005 ◽  
Vol 21 (20) ◽  
pp. 9051-9057 ◽  
Author(s):  
Vishweshwara Herle ◽  
Peter Fischer ◽  
Erich J. Windhab
Keyword(s):  
Flow Visualization ◽  
Shear Bands

A flow visualization and superposition rheology study of shear-banding wormlike micelle solutions

Soft Matter ◽  
2016 ◽  
Vol 12 (4) ◽  
pp. 1051-1061 ◽  
Author(s):  
Hadi Mohammadigoushki ◽  
Susan J. Muller
Keyword(s):  
Diffusion Coefficient ◽  
Flow Visualization ◽  
Correlation Length ◽  
Micellar Solution ◽  
Shear Banding ◽  
Shear Bands ◽  
Wormlike Micelle ◽  
Concentric Cylinders ◽  
Stress Diffusion ◽  
Taylor Couette

In this paper, we use rheometry and flow visualization to study the dynamics of the interface between shear bands in a wormlike micellar solution sheared between concentric cylinders, i.e., in a Taylor–Couette (TC) cell, and to evaluate the stress diffusion coefficient and the stress correlation length in the Johnson–Segalman model.

Analysis of shear bands in slow granular flows using a frictional Cosserat model

2000 ◽  
Vol 627 ◽  
Author(s):  
Prabhu R. Nott ◽  
K. Kesava Rao ◽  
L. Srinivasa Mohan
Keyword(s):  
Scaling Laws ◽  
Shear Bands ◽  
Shear Layers ◽  
Theoretical Description ◽  
Field Variable ◽  
Cosserat Continuum ◽  
Momentum Balance ◽  
Rigid Plastic ◽  
Independent Field ◽  
Cosserat Model

ABSTRACTThe slow flow of granular materials is often marked by the existence of narrow shear layers, adjacent to large regions that suffer little or no deformation. This behaviour, in the regime where shear stress is generated primarily by the frictional interactions between grains, has so far eluded theoretical description. In this paper, we present a rigid-plastic frictional Cosserat model that captures thin shear layers by incorporating a microscopic length scale. We treat the granular medium as a Cosserat continuum, which allows the existence of localised couple stresses and, therefore, the possibility of an asymmetric stress tensor. In addition, the local rotation is an independent field variable and is not necessarily equal to the vorticity. The angular momentum balance, which is implicitly satisfied for a classical continuum, must now be solved in conjunction with the linear momentum balances. We extend the critical state model, used in soil plasticity, for a Cosserat continuum and obtain predictions for flow in plane and cylindrical Couette devices. The velocity profile predicted by our model is in qualitative agreement with available experimental data. In addition, our model can predict scaling laws for the shear layer thickness as a function of the Couette gap, which must be verified in future experiments. Most significantly, our model can determine the velocity field in viscometric flows, which classical plasticity-based model cannot.

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