Animation here . Even though the black fluid profile has a nice feel to it I was planning to have the shape more chaotic at this stage so I may play it down.
It should be three times as long but it works as a preview to get comments on. Might need to add some "fluidness" to the bottom as it will "leak out" shortly after this but pretty close to the final thing now.
Render every 4 seconds of the development in the first sequence. Fairly close to what I want but will need to work on the bottom in the section covered by the last 3 pictures.