Re: Fluid structure interaction module discussion 2

Hi

well for me, you are fist of all starting with all initial conditions = 0 but BC's that tells me your are far from "0". OK you have used a step function with a smooth inlet, but you have a rise time of 0.1 ms while your first time step is 10 ms or some 100 time larger. COMSOL cannot see that rise when starting and then the initial conditions are bad, so it tries, then backtrack , tries again etc, you see it from our solver log.

there are a few ways around:
1) add a few steps so that the flow builds up while you are asking for it with a few points per rise time, or adapt your rise time to the time stepping you have

2) my preferred in addition to 1), add a pressure drop à la Poiseuil or just a linear pressure drop from inlet to outlet along with Y (in your case) and add a parabolic velocity profile (by the way why none "no-slip" on your FSI interface ?)

3) solve the FCD case alone with a fixed structure and use that as initial flow conditions for the FSI

but there might be other points too, I have no time just now to try it out

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Good luck
Ivar