  Convection of liquid metals drives large natural processes and is important
in technical processes. Model experiments are conducted for research purposes
where simulations are expensive and the clarification of open questions
requires novel flow mapping methods with an increased spatial resolution. In
this work, the method of Ultrasound Localization Microscopy (ULM) is
investigated for this purpose. Known from microvasculature imaging, this method
provides an increased spatial resolution beyond the diffraction limit. Its
applicability in liquid metal flows is promising, however the realization and
reliability is challenging, as artificial scattering particles or microbubbles
cannot be utilized. To solve this issue an approach using nonlinear adaptive
beamforming is proposed. This allowed the reliable tracking of particles of
which super-resolved flow maps can be deduced. Furthermore, the application in
fluid physics requires quantified results. Therefore, an uncertainty
quantification model based on the spatial resolution, velocity gradient and
measurement parameters is proposed, which allows to estimate the flow maps
validity under experimental conditions. The proposed method is demonstrated in
magnetohydrodynamic convection experiments. In some occasions, ULM was able to
measure velocity vectors within the boundary layer of the flow, which will help
for future in-depth flow studies. Furthermore, the proposed uncertainty model
of ULM is of generic use in other applications.
