Measurements of the velocity distribution for granular flow in a Couette cell

Fabich, Hilary T.; Brox, Timothy I.; Clarke, Daniel; Seymour, Joseph D.; Codd, Sarah L.; Galvosas, Petrik; Brown, Jennifer R.; Sederman, Andrew J.; Holland, Daniel J.

doi:10.1103/physreve.98.062901

“…These mean collision times relate to the rheology and viscosity of the granular material [180] and would be of great use for refining theoretical descriptions of granular flow. Currently a detailed analysis is underway of the initial data collected with the x /mm x /mm super wide bore drive-shaft unit with a forth coming manuscript submission [174].…”

Section: Preliminary Results and Discussionmentioning

confidence: 99%

“…The following section includes preliminary data from a collaborative study on the flow of granular materials [174].…”

Section: Flow Observations Of Granular Materialsmentioning

confidence: 99%

New Methods for Studying Materials Under Shear with Nuclear Magnetic Resonance

Brox¹

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<p>For over 30 years, nuclear magnetic resonance (NMR) techniques have been used to study materials under shear. Collectively referred to as Rheo-NMR, these methods measure material behaviour due to external stimuli and provide spatially and temporally resolved maps of NMR spectra, intrinsic NMR parameters (e.g. relaxation times) or motion (e.g. diffusion or flow). As a consequence, Rheo-NMR has been established as a complementary technique to conventional rheological measurements. In this thesis, new hardware and experimental methods are presented with the goal of advancing this exciting field through further integration of traditional rheometry techniques with NMR experiments. Three key areas of hardware development have been addressed, including: 1) integrating torque sensing into the Rheo-NMR experiment for simultaneous bulk shear stress measurements, 2) constructing shear devices with geometric parameters closer to those used on commercial rheometers and 3) implementing an advanced drive system which allows for new shear profiles including oscillatory shear. In addition to presenting the design and construction of various prototype instruments, results from validation and proof of concept studies are discussed. This information demonstrates that the hardware operates as expected and establishes an experimental parameter space for these new techniques. Furthermore, these methods have been applied to open questions in various physical systems. This includes exploring the influence of shear geometry curvature on the onset of shear banding in a wormlike micelle surfactant system, observing shear induced structural changes in a lyotropic nonionic surfactant simultaneously via deuterium spectroscopy and bulk viscosity as well as studying interactions of flowing granular materials. The interpretation and implication of these observations are discussed in addition to motivating further studies.</p>

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“…These mean collision times relate to the rheology and viscosity of the granular material [180] and would be of great use for refining theoretical descriptions of granular flow. Currently a detailed analysis is underway of the initial data collected with the x /mm x /mm super wide bore drive-shaft unit with a forth coming manuscript submission [174].…”

Section: Preliminary Results and Discussionmentioning

confidence: 99%

“…The following section includes preliminary data from a collaborative study on the flow of granular materials [174].…”

Section: Flow Observations Of Granular Materialsmentioning

confidence: 99%

New Methods for Studying Materials Under Shear with Nuclear Magnetic Resonance

Brox¹

0

View full text Add to dashboard Cite

<p>For over 30 years, nuclear magnetic resonance (NMR) techniques have been used to study materials under shear. Collectively referred to as Rheo-NMR, these methods measure material behaviour due to external stimuli and provide spatially and temporally resolved maps of NMR spectra, intrinsic NMR parameters (e.g. relaxation times) or motion (e.g. diffusion or flow). As a consequence, Rheo-NMR has been established as a complementary technique to conventional rheological measurements. In this thesis, new hardware and experimental methods are presented with the goal of advancing this exciting field through further integration of traditional rheometry techniques with NMR experiments. Three key areas of hardware development have been addressed, including: 1) integrating torque sensing into the Rheo-NMR experiment for simultaneous bulk shear stress measurements, 2) constructing shear devices with geometric parameters closer to those used on commercial rheometers and 3) implementing an advanced drive system which allows for new shear profiles including oscillatory shear. In addition to presenting the design and construction of various prototype instruments, results from validation and proof of concept studies are discussed. This information demonstrates that the hardware operates as expected and establishes an experimental parameter space for these new techniques. Furthermore, these methods have been applied to open questions in various physical systems. This includes exploring the influence of shear geometry curvature on the onset of shear banding in a wormlike micelle surfactant system, observing shear induced structural changes in a lyotropic nonionic surfactant simultaneously via deuterium spectroscopy and bulk viscosity as well as studying interactions of flowing granular materials. The interpretation and implication of these observations are discussed in addition to motivating further studies.</p>

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