  This paper presents detailed results of neutron imaging of argon bubble flows
in a rectangular liquid gallium vessel with and without the application of
external horizontal magnetic field. The developed image processing algorithm is
presented and its capability to extract physical information from images of low
signal-to-noise ratio is demonstrated. Bubble parameters, velocity components,
trajectories and relevant statistics were computed and analysed. A simpler
version of the code was applied to the output of computational fluid dynamics
simulations that reproduced the experiment. This work serves to further
validate the neutron radiography as a suitable method for monitoring gas bubble
flow in liquid metals, as well as to outline procedures that might help others
to extract data from neutron radiography images with a low signal-to-noise
ratio resulting from high frame rate acquisitions required to resolve rapid
bubble motion.
