Contactless inductive flow tomography for a Rayleigh-Bénard setup with aspect ratio 0.5

The contactless inductive flow tomography (CIFT) allows the reconstruction of the three-dimensional flow field in liquid metals by applying one or more primary magnetic fields to the melt and measuring the flow induced perturbation of those fields outside the melt. From these measurements, the flow is then reconstructed by solving a linear inverse problem using Tikhonov regularisation technique [1].
In recent experiments, CIFT was able to reconstruct the dynamics of the large scale circulation (LSC) in a small modified Rayleigh-Bénard convection cell which was filled with the eutectic alloy GaInSn and consists of a cylindrical vessel with a diameter and a height of 87 mm [2]. Typical time dependent features of the LSC like azimuthal rotations, cessations as well as torsional modes could be visualised by CIFT. Numerical simulations suggest that a sensor arrangement of 8 sensors in azimuthal direction in 3 planes equally spaced over the height of the vessel is a good choice [3]. The developed CIFT configuration allows for measurement times longer than 12 hours with an accuracy of about 20 nT.
Encouraged by these promising results, the measurement system will be adapted to a larger cylindrical Rayleigh-Bénard cell with diameter of 320 mm and height of 640 mm. It is planned to use simultaneously CIFT and UDV in order to reconstruct the global flow while selected flow components are measured in high temporal and spatial resolution with UDV.
In this paper we will present the first design of the arrangement of the excitation coils and the magnetic field sensors. Based on this new setup first reconstructions will be shown. Figure 1 shows a preliminary simulation of the flow in the cylindrical vessel as well as the flow induced magnetic field outside the vessel for a constant primary field in vertical direction with the strength of 1mT.