Check Valves causing insane pressures

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.

Model http://dl.dropbox.com/u/2510110/BasicCheckFail.mdl

Thanks, -Andrew

[K E]

If no one gives a specific answer (sorry I can't), it might be worth doing a search for answers by a previous poster named Arnaud Miege who had a background in Simulink hydraulics. He had a lot of good detailed answers and you might turn up something useful in reading through them.

Answer 1

[Rebecca Carter]

Hello,

I tried out your model and found that if I unchecked 'Use fixed-cost runtime consistency iterations' then it worked fine. It also worked, and much faster, if I used the global solver ODE15s.

--Rebecca

[Guy Rouleau]

If you are interested to know why, I recommend going the 3 papers titled "Real-Time Simulation of Physical Systems Using Simscape"

http://www.mathworks.com/products/simscape/technicalliterature.html