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Updated: Aug 14, 2026
08:43
Calibration Procedures for Orthogonal Superposition Rheology
Published on: November 18, 2020
End effect correction for orthogonal small strain oscillatory shear in a rotational shear rheometer
Ran Tao1,2, Aaron M Forster1
1Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Rheologica Acta
|August 13, 2026
Summary
Orthogonal superposition (OSP) rheology calibration is improved by accounting for end-effect errors. This study quantifies corrections for steady shear and orthogonal oscillatory shear, enhancing measurement accuracy for complex fluids.
Area of Science:
- Rheology
- Fluid Dynamics
- Material Science
Background:
- Orthogonal superposition (OSP) rheology measures structural dynamics in complex fluids under shear flow.
- Commercial availability of OSP geometries increases its routine use.
- Understanding calibration and flow field influences is crucial for accurate measurements.
Purpose of the Study:
- To calibrate OSP rheology using viscosity standards.
- To quantify end-effect corrections in steady shear and orthogonal oscillatory shear.
- To investigate flow field effects using computational fluid dynamics.
Main Methods:
- Calibration measurements using Newtonian fluids (0.01-331 Pa s) on a commercial shear rheometer with double-wall concentric cylinders.
- Quantification of end-effect factors for steady shear and orthogonal oscillatory shear.
- Computational fluid dynamics (CFD) simulations to analyze flow fields and end-effect contributions.
Main Results:
- Steady shear viscosity corrections ranged from 16-21%.
- Orthogonal complex viscosity errors ranged from 19-25%.
- CFD revealed approximate linear shear deformation, with end-effects contributing 9% (pressure) and 8% (shear rate) to overestimation.
Conclusions:
- End-effect corrections are essential for accurate OSP rheology.
- CFD simulations provide insights into flow behavior and error sources.
- Operational knowledge and defined measurement windows are critical for instrument accuracy.
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