With the recent development of large signal sources in noble gases (3He and 129Xe) , we propose to use MR to explore turbulence in low Prandtl number fluids. The rapid velocities will be measured with a spiral sequence having imaging times (TR) less than 10ms. These experiments should provide velocity data of unparalleled quality, and help to address issues of scaling behavior for turbulent flow in this Prandtl number regime. An interesting point is that this technique could also provide data for the velocity field over a range in space, so that it would be unnecessary to invoke the usual Taylor frozen turbulence hypothesis in order to obtain spatial information. At the very least, this technique could provide detailed, non-invasive information of the mean flow velocity fields in systems comparable to the cryogenic turbulence experiments noted above. Such information is unavailable by any other means of which we are aware. The unique combination of hyperpolarized gas imaging, large gradients and gradient slew rates, and excellent computational facilities necessary for this project are available solely at the Center. We expect to accomplish the following goals: 1. We will adapt a spiral pulse sequences (2D and 3D) to study turbulent flows, including both convectively driven and pressure or grid driven flow. 2. We will obtain the mean flow fields for convective and other systems as in 1. 3. We will obtain space-time resolved measurements of the velocity fields for the systems in 1.
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