Complex Variable for Helmholtz FSI Block Solver

[KrDeltaIntergrale]

Hi

I am trying to utilize the block solver to couple the Helmholtz and StressSolver for an FSI problem as demonstrated in the group of tests/ShoeboxFSI group of test cases. I am having trouble getting the complex variable defined in the stress solver correctly so it is readable in the Helmholtz solver and the block.

I have tried copying the elastic solver from the test case and recieved an error on not having a complex variable

I have tried the following to define a acceptable variable
Variable = Displacement
~
Variable = -dofs 2 displacement
~
Variable = U[displacement:1 displacement im:1 displacement:2 displacement im:2 ]
Variable DOFS = 2
~
Variable = U[displacement:1 displacement im:1 displacement:2 displacement im:2 ]
Variable DOFS = 4
~
Variable = U[[displacement:1 displacement im:1] [displacement:2 displacement im:2 ]]
Variable DOFS = 2

Any other suggestions?

[raback]

Hi

Its internal magic. The key is the "Harmonic Mode" keyword (see ShoeboxFsiHarmonic2D) that make a transient equation to become a harmonic one. The Helmholtz solver was initially written for the complex valued problem whereas the stress solver just uses "d/dt -> iw".

Why cant you use directly the test case conventions?

-Peter

[KrDeltaIntergrale]

The block solver worked when I removed some of the Helmholtz BC (Plane Wave) from the far field boundary, it apparently mucks up the default displacement variable which is masked as U when the harmonic modes is turned on. I think the preferred way to set the far field emitting boundary is tangential velocity = 0 but im not sure, it my be only applicable to the linearized acoustics solver.

[raback]

Hi

Helmholtz equation can only be given normal velocity.

-Peter