Boundary Conditions for FSI

[Emilie]

Dear Elmer users and developers,

I'm trying to run a fluid-structure simulation in 2D axisymmetric coordinates. My flow domain is enclosed by elastic cylindrical wall. I impose sinusoidal time variation of inlet velocity profile and I'd like to compute the flow field when the wall of the pipe is deformed by the pressure of the fluid. The computed pressure variation along the length of the pipe is as expected, but the problem is that the pressure in the nodes located at the fluid-structure interface is all the time equal to zero. I cannot figure out what should be the correct type of boundary conditions I should use.

The numbering of boundaries in my *.sif file is as follows:
1 - Fluid inlet
2 - Bottom section of the elastic wall (the surface of the artery on the inlet side)
3 - Outer surface of the elastic wall
4 - Top section of the elastic wall (artery surface on the outlet side)
5 - Fluid outlet
6 - Axis of symmetry - identical to the y coordinate axis
7 - Inner surface of the elastic wall - the interface between fluid and solid

Could anyone please give me a hint what boundary conditions I should change/remove/add ?

Thank you very much,

Emilie