[FluidEmil]

Hi all,

So im new to fluent, and i want to simulate the opening of a check valve by simulating a spring force on one face of the valve and the fluid pressure on the other. I want to do this in 2D
I have set this up with the 6DOF solver and set it to 1DOF translation with a small spring constant of 20N/m. The fluid is water, and i've set a velocity inlet based on a UDF where the flow is = 10*current_time, up until 0.02s when the flow is 0.2m/s. The outlet is a pressure outlet with 0pa static pressure.

My problem is that unless i use very very small time steps of 1e-10 s, even at very small flow rates, the solver spits out huge resulting forces on the face of the valve. This only happens for fluids with high densities, if i use air for example, i am able to simulate the valve movement just fine.

What could the issue be?

i have uploaded a pic of the pressure contour. The inlet is to the left. This is at a time step in the order of 1e-09 seconds.