Characterising stationary and translating vortex flow using magnetic resonance

We report magnetic resonance (MR) velocity and diffusion maps in three directions for stationary vortices (Taylor vortex flow - TVF) and velocity maps for translating vortices (vortex flow reactor - VFR) produced in a Couette cell. Motion artefacts in the translating vortex flow are removed by synchronising data acquisition with the translation period of the vortices. MR propagator experiments, which measure the conditional probability density for displacement, were performed to characterise molecular displacements in these systems. Simulations were performed using the experimental velocity and diffusion maps to aid interpretation of experimentally measured propagators and enable characterisation of the macro-mixing and transport properties within TVF and VFR systems. These simulations enabled molecular transport and mixing to be assessed over longer-time scales than are accessible experimentally, allowing plug flow, by-pass flow and inter-vortex mixing to be quantified.