I'm working on a system model that uses a set of 4 check valves to rectify a sinusoidal flow. Right now I am seeing some very strange behavior from the check valves and I'm not sure what's going on. In order to try and eliminate issues I broke the problem down to a very simple model and I'm still seeing issues. Basically when the flow gets reversed pressure readings from before the check valve behind to oscillate between their positive and negative values, basically each consecutive value appears to be the inverse of the previous value. I've linked to my model below. If anyone has and suggestion as to what is happening I would love to hear it.