For a project of mine I am working with COMSOL in order to simulate the flow of a fluid in a reactor vessel which is mixed by a helical blade. In order to do this I figured I would use COMSOL's rotating machinery option, since it seems to be exactly what I need. One problem: I cannot for the life of me find how to add a fluid into the model. I have a vessel and a blade (blade is inserted into the vessel). I need to fill the vessel with a fluid and spin the blade in order to get some useful data. Does anyone have any experience with this?