Search found 74 matches

by panosvar
31 Jan 2020, 18:22
Forum: ElmerSolver
Topic: 2d simulation of acoustic wave propagation
Replies: 58
Views: 3504

Re: 2d simulation of acoustic wave propagation

To have the same sources Elmer definitions should be written as BCs for the normal pressure gradient. Could you give me an example of how I should have written such an equation? I guess the Comsol model has PML BCs on the edges x = const. Yes it has. The simple impedance BC of Elmer is best suited ...
by panosvar
31 Jan 2020, 17:21
Forum: ElmerSolver
Topic: 2d simulation of acoustic wave propagation
Replies: 58
Views: 3504

Re: 2d simulation of acoustic wave propagation

I've attached how the same focus looks in Comsol. Doesn't look the same at all. In Comsol what I use, is the Normal Acceleration setting as I stated above.
by panosvar
30 Jan 2020, 22:18
Forum: ElmerSolver
Topic: 2d simulation of acoustic wave propagation
Replies: 58
Views: 3504

Re: 2d simulation of acoustic wave propagation

My phases are in radians indeed. Do you mind uploading a picture of your results?
by panosvar
30 Jan 2020, 18:35
Forum: ElmerSolver
Topic: 2d simulation of acoustic wave propagation
Replies: 58
Views: 3504

Re: 2d simulation of acoustic wave propagation

Hi Peter, I've corrected the link you can try now: https://mega.nz/#!ySoymCLA!J7qImB2au1E2HYujEjn3mlLDy9EBpU57zOiIrfmYD0Y . This is supposed to produce a trap somewhere on the top right area between the two arrays of transducers. Run test.sif to run the simulation. Also, I uploaded the model summary...
by panosvar
30 Jan 2020, 15:39
Forum: ElmerSolver
Topic: 2d simulation of acoustic wave propagation
Replies: 58
Views: 3504

Re: 2d simulation of acoustic wave propagation

To be more specific, in COMSOL every transducer surface is assigned a Normal Acceleration with the equation 1*accel*exp(-1j*(phase[i])) and accel = 5.6849E5 1/s² , where phase[i] is the phase of the ith transducer that is required in order to produce a specific trap in space. Then, by running the BE...
by panosvar
28 Jan 2020, 17:58
Forum: ElmerSolver
Topic: 2d simulation of acoustic wave propagation
Replies: 58
Views: 3504

Re: 2d simulation of acoustic wave propagation

Hi, The description the source is represented by exp(1j*k*r) is not complete, there has to be an additional time-dependent part. Well, I now try to be quite specific since this appears to be necessary in order to make progress. If each transducer is supposed to create a plane wave (that is, a wave ...
by panosvar
28 Jan 2020, 16:14
Forum: ElmerSolver
Topic: 2d simulation of acoustic wave propagation
Replies: 58
Views: 3504

Re: 2d simulation of acoustic wave propagation

Hi At 40 kHz the wavelength is around 8.5 mm. On the other hand, with standard nodal FEs you need at least ~10 elements per wave. Hence, your mesh size, h, should be smaller than 1 mm in order to capture the phenomena. Could the insufficient mesh density be a problem? -Peter I'm meshing in Salome. ...
by panosvar
27 Jan 2020, 15:07
Forum: ElmerSolver
Topic: 2d simulation of acoustic wave propagation
Replies: 58
Views: 3504

Re: 2d simulation of acoustic wave propagation

Also, with lower frequencies (like 1kHz) I see some basic expected output, like if I emit a pressure wave from the bottom middle transducer, which is not the case for 40kHz. So, we come back to the suggestion that either my mesh is not good, or Elmer solver is just not enough for higher frequencies....
by panosvar
27 Jan 2020, 14:49
Forum: Installation & compilation
Topic: install MUMPS solver (Windows)
Replies: 3
Views: 2800

Re: install MUMPS solver (Windows)

Installing the Elmer VM did the trick for me.
by panosvar
27 Jan 2020, 13:22
Forum: ElmerSolver
Topic: 2d simulation of acoustic wave propagation
Replies: 58
Views: 3504

Re: 2d simulation of acoustic wave propagation

mika wrote:
26 Jan 2020, 18:23
I made a mistake, the intention was to write "either exp(iwt) or exp(-iwt)]". So Elmer assumes the representation p(x,t) = P(x)exp(iwt) and this is the sole option.
In my matlab code, the source is represented by exp(1j*k*r), where k is the wavenumber and r is the coordinate vector.