Echo-Planar-Imaging Studies of Turbulent Flow

The dependence of the NMR signal from turbulent flow in echo-planar images on flow rate has been investigated for pipe flow, for Reynolds’ numbers up to 6300. The short imaging time possible using echo-planar images essentially “freezes” the random motion of turbulent fluids and 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 flow have been analyzed to characterize the temporal and spatial characteristics 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 turbulent flows.