Flow imaging

Rombaoh K, Laukemper-Ostendorf and Blumler P 1998 Applioations of NMR flow imaging in materials soienoe Spatially Resolved Magnetic Resonance, Proc. 4th Int. Cent, on Magnetic Resonance Microscopy and Macroscopy ed P Blumler, B Blumioh, R E Botto and E Fukushima (Weinheim Wiley-VCFI) pp 517-29... 

History of upward flame propagation and extinction in lean limit methane/air mixture. Square 5 cm x 5 cm vertical tube. Green color frames indicate PIV flow images. Red color represents direct photography of propagating flame. Extinction starts just after frame c. Framing rate... 

Yang, M. et al. (1999) Real-time ultrasound process tomography for two-phase flow imaging using a reduced number of transducers. IEEE Trans. Ultrason. Ferroelectr. Freq. 

Steinke W, Kloetzsch C, Hennerici M. Carotid artery disease assessed by color Doppler flow imaging correlation with standard Doppler sonography and angiography. AJR Am J... 

Fig. 2.6.5 Hardware for high field NMR remote probe in (c) contains a relatively large saddle-detection. Photographs (a) and (b) show la- coil and is used for (flow) imaging. The detec-boratory-built remote detection probes with tor probe in (d) contains a microsolenoid coil both rf coils built into the same body (c), (d) for optimized mass sensitivity, which is parti-and (e) are detector-only remote probes that cularly useful for microfluidic NMR applica-can be inserted from the top or bottom into the tions. The same probe is shown in (e) with a NMR imaging assembly, so that the well mounted holder for a microfluidic chip that is...

S. Yao, A. G. Fane, J. M. Pope 1997, (An investigation of the fluidity of concentration polarisation layers in crossflow membrane filtration of an oil-water emulsion using chemical shift selective flow imaging), Mag. Reson. Imag. 15, 235. 

We would like to thank Peter Blunder and Simone Laukemper-Ostendorf who initially established the collaboration between the company Membrana and the RWTH. They started NMR flow imaging studies to characterize filtration in hemodialyzer modules, and Volker Gobbels measured the first 2D VEXSY data of counterflow in such applications. All experimental work has been accomplished in the Magnetic Resonance Center (MARC) directed by Bernhard Bliimich, whose support and leadership is greatly acknowledged. 

K. Rombach, S. Laukemper-Ostendorf, P. Bluemler 1998, (Applications of NMR flow imaging in materials science), in Spatially Resolved Magnetic Resonance, eds. P. Bluemler, B. Bluemich, R. Botto, E. Fukushima, Wiley-VCH, New York. 

A velocity profile u(r) is obtained using MRI flow imaging and, with respect to radial position r, the values of shear rate y(r), ranging from zero at the tube center to a maximum at the tube wall, can be calculated from the velocity profile as local velocity gradients ... 

McKee, S. L., Dyakowski, T., Williams, R. A., and Bell, A., Solids Flow Imaging and Attrition Studies in a Pneumatic Conveyor, Powder Tech., 82 105(1995)... 

Brain infarction was the first clinical application of SPECT. Decreases in relative cerebral perfusion were imaged by SPECT for diagnosis. Decreased rCBF is visualized in the form of decreased signal on SPECT and PET. The sensitivity and specificity of brain SPECT for infarct localization are 85.5% and 97.6%, respectively [99]. Blood-flow imaging is useful in the evaluation of response to therapy in patients with cerebrovascular diseases [100]. 

Figures 25 and 26 show how the combined application of MRI and flow imaging allows us to study deposition of fines within fixed beds. This is a common problem in reaction engineering. For example, during process operation, attrition of the catalyst occurs and the resulting fines are deposited throughout the bed. The deposits then influence the flow paths through the bed, thereby influencing the operating conditions within the bed (e.g., pressure drop) and chemical conversion.

Until recently, MR flow imaging in fixed beds was limited to imaging pseudosteady-state phenomena. Data acquisition times for 2-D flow images were typically several minutes, or even tens of minutes, and successful imaging of the velocity field requires the flow field to be stable over the data acquisition time. Therefore, flow imaging studies had been restricted to relatively low flow rates (Re <200 based on the diameter of the packing elements) (82). Figure 27 shows data for a narrow packed bed characterized by a column-to-particle diameter ratio of 2 spheres of diameter 19 mm were packed within a 38-mm-diameter column. Flows at two different values of Reynolds number are shown (Re — 200 and 300). 

Fig. 27. MR flow images of unsteady-state flow of water through a fixed bed with a column-to-particle diameter ratio of 2. Velocity maps measured by a standard spin-echo phase encoding velocity measurement and the GERVAIS pulse sequence are compared for values of Re of (a) 200 and (b) 300. In each case (i) is the standard spin-echo phase encoding velocity image, and (ii) and (iii) are the and flow vectors measured using GERVAIS.

Figure 13.. Comparison of theoretical analysis and empirical NMR imaging of fluid flow during extrusion. Limiting cases for theoretical analysis (a), the velocity profile as a function of position with no pressure gradient in the z-direction (b), the velocity profile as a function of position with no net flow through the extruder. Limiting cases for empirical analysis by NMR flow imaging (c), no pressure gradient in the z-direction (die open) (d), no net flow through the extruder (die closed).[Reproduced with permission from Ref.61].

Active mixing of droplets - two-electrode flow imaging... 

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