Elmer Discussion Forum

Hello teofil,
as you can read before in this thread, Helmholtz equation is steady state. It is not transient. So, only if you can obtain result from dynamic harmonic analysis, it is possible to use it in helmholtz solution (for each frequency). Maybe some kind of modal superposition?

BR
Irek

Hello,
by the way, are there any chances for pml (perfectly matched layer) boundary condition in helmholtz?
Or maybe it should be solver for one or more elements layers.

BR
Irek

I think, problem is solved
I modified helmholtz.edf file, now convection velocity is in material section

below is modified file.
I think this is useful modification.

BR
Irek

I think, there is a problem with convection velocity statement processing in Helmholtz solver. When convection velocity is set in ElmerGUI in Helmholtz page - it is ignored. It sets convection velocity in Equation section of sif file. When this statement ie. ,,convection velocity 1 = 10" in Mat...

Hi, I think, that exterior boundary condition is not necessary. For example, in gmsh, just do not set boundary as physical group. In mesh file there is only volume mesh.

BR
IC

Hi! I would like to add another doubt to this subjet, this time a bit more specific and even more application oriented. Acoustics absorbent material manufacturers inform the absorption coefficient as the material property that describes the sound absorption capabilities, measured according to ASTM ...

OK. Problem not solved, but bypassed

I did the same work as ElmerParam+R but in Octave with sed

BR.
Irek

hello everybody. I'm not shure, if it is good formum for my problem, but I try I am trying to use ElmerParam, but: example optimisation in R of rosenbrock function from ElmerParam manual gives me error: optim(c(0,0),elmer_param) Error in fn(par, ...) : CHAR() can only be applied to a 'CHARSXP', not ...

Becouse I was in hurry, I did it in Ansys. So, if You find any solution, it will be appreciated.

I want to analyse interior space of a rectangular box. I wonder if it is posible to have elastic walls for helhmoltz equation. Excitation is in form of acoustic pressure in particular point inside box. So I want to analyse elastic box with sound source inside. Do You think it is possible? And How? B...