ECHO-PLANAR-IMAGING STUDIES OF TURBULENT-FLOW

The dependence of the NMR signal from turbulent flow in echo-planar im ages on flow rate has been investigated for pipe flow, for Reynolds' n umbers up to 6300. The short imaging time possible using echo-planar i mages essentially ''freezes'' the random motion of turbulent fluids an d permits the study of individual eddies and intermittency, By use of appropriate approximations, the magnitude signal can be related to the fluid velocity shear in one direction. Sequential images of pipe how have been analyzed to characterize the temporal and spatial characteri stics of pipe flow at, below, and above the onset of turbulence. These experiments show that echo-planar imaging may have unique advantages for the spatial mapping and temporal characterization of some turbulen t flows. (C) 1996 Academic Press, Inc.