Elmer Discussion Forum

If I make these changes in two places, the answer becomes much closer Complex(KIND=dp) :: MASS(nd,nd), STIFF(nd,nd), FORCE(nd) MASS(:,:) = (0._dp, 0._dp) STIFF(:,:) = (0._dp, 0._dp) FORCE(:) = (0._dp, 0._dp) DAMP(:,:) = (0._dp, 0._dp) The real part is much closer. But the imaginary part is way, way...

Hi Kevin,

It's much better making all matrices complex.

Do you know what the problem is?

Hi Kevin,

I had noticed that too. But I need to have a complex damping matrix.

Is this a fault of the complex solver?

I need to create complex valued matrices for an eigenvalue problem I am solving. I have modified WaveSolver.f90 to suit my requirements, mainly by declaring damping matrix and sound reaction term as complex. I've attached the modified solver module, the sif and mesh files in the zip file below. To v...

Hi Marc, I think that if you have conflicting flags then the latter one usually prevails (in gnu compiler stack). So your first assumption should be ok. I found a discussion on the topic that may be relevant: https://stackoverflow.com/questions/40563269/passing-multiple-std-switches-to-g -Peter Hi ...

Hi Rich,

I'll check these tutorials and get back to you.

Thanks.

Hi Kevin, The manual says to set the keyword "Eigen System Damped" to true when we add damping term to the equation. I did this for a toy problem whose analytical eigenvalues are known, and got the right result. Further, it also says not to set the keyword "Eigen System Complex" ...

In the "Solving eigenvalue problems" chapter of the Solver manual, it is mentioned that the keyword "Eigen System Complex" can set to true when the system matrices are complex. How can complex system matrices be created? Because for linear elasticity problems, density, which form...

Hi Rich,

I am yet to write the sif for this case. Without the source, it is just a plane Helmholtz equation in harmonic form applied to an enclosure.

Hi Peter, The source is a flame in the combustor. The acoustic waves interact with the flame and the heat released has a harmonic variation, but with a phase lag. The response of the heat release depends on the frequency of the acoustic waves. The phase determines if the amplitude of the acoustic wa...