FLUENT - VOF to model draining tank, swirling liquid, vortex at the drain drain.
It is possible to model a draining tank filled with a
swirling liquid, and to capture the vortex that forms at the drain. The
goal was to pinpoint the time at which the first gas reaches
A pressure inlet was used to maintain the tank pressure (otherwise the
assumption of incompressibility in FLUENT is violated, and one gets
pockets of gas in the liquid). A Custom Field Function was used to set
up an initial swirl velocity. The drain was treated in a
counter-intuitive manner: a velocity inlet was used as the boundary
condition, with the direction vector pointing out of the tank, and with the
volume fraction of liquid equal to unity.