[Libmesh-users] Unusual results of transient RB with 7 parameters

[吴家桦Gauvain <cau...@gm...>]

Hi all,

I am trying to make a transient thermoelastic RB model. Both Internal heat
flux and external heat exchange described by Newton's law of cooling(Robin
boundary condition) are considered. It works well when the three thermal
conditions (heat flux, heat transfer coefficient and ambient temperature)
are chosen as parameters. However, abnormal results are observed when the
material properties (Young's modulus, Poisson's ratio, thermal expansion
coefficient and heat conductivity) are added as parameters: Three
displacement components remain 0 and the temperature increases drastically
as the time goes by. What's more, I notice that the difference between the
first and the second POD eigenvalues is extremely large:

POD Eigenvalues:
eigenvalue 0 = 4.4536e+08
eigenvalue 1 = 2.45303e-07
...
last eigenvalue = -1.90536e-07

The matrix assembly should not pose problem because it runs well in steady
case and I simply copy the assembly functions without any modification.
Thus I am really confused and I cannot figure out where the problem is.
Could you give me some suggestions? Thanks a lot.

Gauvain
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