High Field MicroMRI Velocimetric Measurement of Quantitative Local Flow Curves

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Abstract
Performing rheo-microMRI velocimetry at high magnetic field with strong pulsed field gradients has clear advantages in terms of (chemical) sensitivity and resolution in velocities, time and space. To benefit from these advantages some artefacts need to be minimized. Significant sources of such artefacts are chemical shift dispersion due to the high magnetic field, eddy currents caused by the pulsed magnetic field gradients, and possible mechanical instabilities in concentric cylinder (CC) rheo-cells. These in particular hamper quantitative assessment of spatially resolved velocity profiles needed to construct local flow curves (LFCs) in CC geometries with millimeter gap sizes. A major improvement was achieved by chemical shift selective suppression of signals that are spectroscopically different from the signal of interest. By also accounting for imper-fections in pulsed field gradients, LFCs were obtained that were virtually free of artefacts. The approach to obtain quantita-tive LFCs in millimeter gap CC rheo-MRI cells was validated for a Newtonian and a simple yield stress fluids, which both showed quantitative agreement between local and global flow curves. The acquisition of LFCs during heterogeneous and transient flow of a fat crystal dispersion demonstrated that local constitutive laws can be assessed by rheo-microMRI at high magnetic field in a non-invasive, quantitative and real-time manner.
Funding Information
  • Nederlandse Organisatie voor Wetenschappelijk Onderzoek (13386)

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