2.6. In the liquid volume, there is also closed loop, thermo-syphon type recirculation with a different total mass
flow R(liquid) kg/s .Again, the recirculation consists of an upward boundary layer flow adjacent to the neck wall,
with a total mass flow of R(liquid) plus the boil-off mass flow, while the centre of the liquid has a total downward
mass flow R concentrated into a central jet. Evaporation of the liquid only takes place at the surface as the boundary
layer flow turns over and flows radially inwards along the surface to the central downward jet. Further studies on
large scale storage systems are needed to measure the scale of the recirculations and the associated build-up of
stored thermal energy in the liquid.