Measurement of vorticity diffusion by NMR microscopy.
In a Newtonian fluid, vorticity diffuses at a rate determined by the kinematic viscosity. Here we use rapid NMR velocimetry, based on a RARE sequence, to image the time-dependent velocity field on startup of a fluid-filled cylinder and therefore measure the diffusion of vorticity. The results are consistent with the solution to the vorticity diffusion equation where the angular velocity on the outside surface of the fluid, at the cylinder's rotating wall, is fixed. This method is a means of measuring kinematic viscosity for low viscosity fluids without the need to measure stress.
Brown
Jennifer R
JR
Victoria University of Wellington, School of Chemical and Physical Sciences, The MacDiarmid Institute of Advanced Materials and Nanotechnology, PO Box 600, Wellington 6012, New Zealand. jbrown@coe.montana.edu
Callaghan
Paul T
PT
D000465:Algorithms; D003198:Computer Simulation; D004058:Diffusion; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008853:Microscopy / Q000379:methods*; D008956:Models, Chemical; D016062:Porosity; D012212:Rheology / Q000379:methods*