Hi, I'm trying to model a compensation device in a hydraulic system. Basically, I have a closed pipe that contains a body of liquid (water glycol) and as time elapses this fluid is subject to a cooling effect. This results in contraction and hence a pressure decrease which is subsequently compensated for by the injection of additional fluid. What I'm struggling to understand are the exact dynamics of contraction and how this affects the pressure (for example, does a vacuum form etc.?). If anybody can impart some pointers/direct me to some good literature then I would be extremely grateful! Cheers if you can help.