Painting Taylor vortices with cellulose nanocrystals: supercritical spectral dynamics
Preprint, 2023

We study the flow stability and spatio-temporal spectral dynamics of cellulose nanocrystal (CNC) suspensions in a custom Taylor-Couette flow cell using the intrinsic shear induced birefringence and liquid crystalline properties of CNC suspensions for flow visualizations for the first time. The analysis is performed at constant ramped speed inputs of the independently rotating cylinders for several cases ranging from only inner or outer rotating cylinders to three counter-rotation cases. All CNC suspensions have measurable elastic and shear thinning, both increasing with CNC concentration. We show that the flow patterns recorded are essentially Newtonian-like, with non-Newtonian effects ranging from a decrease in wavenumbers to altering the critical parameters for the onset of instability modes. Outer cylinder rotation flow cases are stable for all concentrations whereas inner cylinder rotation flow cases transition to axisymmetric and azimuthally periodic secondary flows. However, unstable counter-rotation cases become unstable to asymmetric spiral modes. With increasing CNC concentration a counter-rotation case was found where azimuthally periodic wavy patterns transition to asymmetric spiral modes. In contrast to polymeric solutions of similar low to moderate elasticity and shear thinning, the shear-thinning region of CNC suspensions is expected to lead to the breakdown of the chiral nematic phase, whose elastic constants constitute the dominant structural elasticity mechanism. Thus, we interpret the Taylor-Couette stability of the CNC suspensions as dominated by their shear-thinning character due to the expected loss of elasticity in nonlinear flow conditions.

Taylor-Couette instabilities

spectral dynamics


small-angle X-ray scattering

cellulose nanocrystals


Reza Ghanbari

Chalmers, Industrial and Materials Science, Engineering Materials

Sajjad Pashazadehgaznagh

Chalmers, Industrial and Materials Science, Engineering Materials

Kesavan Sekar

Chalmers, Industrial and Materials Science, Engineering Materials

Kim Nygård

Lund University

Ann Terry

Lund University

Marianne Liebi

Chalmers, Physics, Materials Physics

Aleksandar Matic

Chalmers, Physics, Materials Physics

Roland Kádár

Chalmers, Industrial and Materials Science, Engineering Materials

Development of a new rheometer system at MAX IV

The Chalmers University Foundation, 2019-03-01 -- 2021-12-31.

MAX IV Laboratory, 2019-03-01 -- 2021-12-31.

Subject Categories

Computational Mathematics

Paper, Pulp and Fiber Technology

Other Physics Topics

Fluid Mechanics and Acoustics


Basic sciences

Areas of Advance

Materials Science



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2/9/2024 1