Chapter 5: Transport in Structured Media: Multidimensional PFG-NMR Applied to Diffusion and Flow Processes

The consideration of flow, or net transport, of a fluidic system adds to the further complication of phase shifts in the NMR signal, as well as limitations of measurement techniques due to inflow/outflow effects and blurring. On the one hand, flow may require the use of compensation techniques, many of which were developed out of necessity in medical research but have also been applied in the field of engineering. On the other hand, the existence of flow with its defined preferential direction of material transport also raises opportunities to investigate the spatial and temporal behaviour of flow itself, and of the way a fluid interacts with its solid environment, leading to correlations of motion in different directions or at different times. PFG-NMR is unique in its versatility to sample these correlations and to combine them with spectroscopic and spatial resolution. This Chapter will present concepts and recent applications in the field of multidimensional approaches to fluid transport.