With some insane amount of work could be done in ilustrator, with some real life photos for reference.
But they are more easity done taking a photo... you gessed... Ink on a water tank.
https://www.google.com/search?q=ink+on+a+tank+photo+tutorial
They also can be done in 3D with a specialized particle generator and render engine: https://www.afterworks.com/FumeFX/Overview.asp
or try blender