Time dependent Hinge fluid interaction

I am modeling an artificial heart valve that utilizes hinges as seen in the file included. In the human body the valve hinges are passive which means they open and close depending on varying blood flow. In my model, I can get the hinges to move back and forth if I apply a pressure to one side of the hinge, however, as soon as I add a steady fluid flow I get the following error. "Failed to find consistent initial values.
Segregated group 2
Attempt to evaluate real square root of negative number."


Eventually I would like to add a time -dependent fluid flow that mimics blood flow through the heart but for now I am trying to get the simplest case with steady flow to provide an answer.

I would really appreciate any suggestions on how to precede with this kind of set up.

Thanks in advance!

Charlott