Rob
Ansys Employee

OK. If you want to model the liquid flow it has to have space to move: squashing liquids can be done but it's often not needed. If you want to add a pressure into the system and look at a piston moving which then displaces liquid at the other end you may want to look at Mechanical with some fluid elements. We can do it all in Fluent using moving mesh, 6DOF etc but the cost is much higher: it's worth paying if you need all of the information.