Observing curved flow using RUFIS

The rotating ultra-fast imaging sequence (RUFIS) is used to image spins flowing through the curved portion of a 180 degrees U-tube with a circular cross section and a ratio of inner diameter to curvature diameter of 0.41. A velocity-encoding preparation sequence is used with RUFIS to measure quantitatively the axial velocity distribution for spins under steady-flow conditions. The resulting velocity contours confirm that higher velocity spins migrate toward the outer wall of the curve as the Dean number is increased.