Coupled Fluid-Structure Eigen Analysis

[raback]

Hi Kevin,

The HelmholtzStructure cases are hierarchical: structure -> acoustics. The FsiShoebox* cases are strongle coupled: structure <-> acoustics.

-Peter

[kevinarden]

using the ShoboxFsiEigen2d test case with
Density = 2710.0
Youngs Modulus = 70e9
Poisson Ratio = 0.3
The beam frequency should be 87 Hz in air and 55 Hz in water

with

$ AirDensity = 1.0
$ SoundSpeed = 300

ElmerSolver reports
EigenSolveComplex: EIGEN SYSTEM SOLUTION COMPLETE:
EigenSolveComplex:
EigenSolveComplex: Number of converged Ritz values is: 10
EigenSolveComplex: Computed Eigen Values:
EigenSolveComplex: 1 (1.04082768848625157E-004,-1.08456037487612890E-008)
EigenSolveComplex: 2 (-7.9012503238339047,-4.0733589099508940)
EigenSolveComplex: 3 (-7.8696137561585102,4.1349833785406878)

Changing the fluid density results in the imaginary part of the complex eigenvalue 1

results.png (15.77 KiB) Viewed 78 times

Any fluid density over 18 results in a solver error, water would be 1000.0