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Tomographic Techniques for Measuring Fluid Flow Properties

Choi, Y.J., Mccarthy, K.L., Mccarthy, M.J.
Journal of food science 2002 v.67 no.7 pp. 2718-2724
corn syrup, image analysis, magnetic resonance imaging, process control, product quality, tomato juice, tomography, viscosity
Experimental fluid velocity profiles can be readily obtained by using tomographic techniques. Combining measurements of a fluid velocity profile with a simultaneous pressure drop permits the evaluation of rheological properties. In order to control a process and to assure product quality, it is useful to monitor the rheological properties in-line or on-line. Two tomographic techniques, magnetic resonance imaging (MRI) and ultrasonic Doppler velocimetry (UDV), were used to obtain velocity profiles for a 65.7 °Brix corn syrup solution and a 4.3 °Brix tomato juice. The UDV technique provided velocity profiles that compared well with the MRI method. For the corn syrup, the shear viscosity of 1.37 Pa-s (UDV) and 1.51 Pa-s (MRI) agreed well with the offline measurement of 1.57 Pa-s. The tomato juice was best characterized as a Bingham plastic fluid. The yield stress ranged from 4.44 Pa to 4.70 Pa, which matched well with the off-line value of 4.50 Pa. The strengths and limitations of both techniques are presented.