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Updated: Mar 19, 2026

Quantifying Mixing using Magnetic Resonance Imaging
Published on: January 25, 2012
Quantitative velocity distributions via nuclear magnetic resonance flow metering
Keelan T O'Neill1, Einar O Fridjonsson1, Paul L Stanwix1
1School of Mechanical and Chemical Engineering, University of Western Australia, Crawley, WA 6009, Australia.
Abstract:
We demonstrate the use of Tikhonov regularisation as a data inversion technique to determine the velocity distributions of flowing liquid streams. Regularisation is applied to the signal produced by a nuclear magnetic resonance (NMR) flow measurement system consisting of a pre-polarising permanent magnet located upstream of an Earth's magnetic field NMR detection coil. A simple free induction decay (FID) NMR signal is measured for the flowing stream in what is effectively a 'time-of-flight' measurement. The FID signal is then modelled as a function of fluid velocity and acquisition time, enabling determination of the velocity probability distributions via regularisation. The mean values of these velocity distributions were successfully validated against in-line rotameters. The ability to quantify multi-modal velocity distributions was also demonstrated using a two-pipe system.
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