Elmer Discussion Forum

Thanks Kevin. That is consistent with my results then. It looks like the only mechanism available right now for my tests case is Scanning with Stress solver + Helmholtz, and that the Eigen solver and the Wave solver both do not currently solve for the case. I did track down the problem wiht my 2d gu...

I got around to testing the 2d beam case. I'm not sure what I am seeing is what is expected or not. I ran a scanning simulation of the immersed beam in both air and water. In Air the first resonance of the beam is at around 84 Hz. In Water the first resonance of the beam is around 51 Hz. This is wit...

One test I would like to do that I have gotten to is to try frequency scanning on the beam in fluid case Kevin gives here to see if the fluid coupling gives the expected results. I probably won't get to that for a week or so given my free time availability for the next bit. The idea would be to scan...

I finally got some time to build out a simplified 2D version of the guitar model. I think the fluid structure modal analysis is working correctly, or at least I get results that are consistent with my expecations, and driving changes either the fluid or the structure causes coupled changes in the jo...

I'll be happy to contribute a case once I get this working well enough. I've been trying transient simulations and ran into a few problems with the model set up I was using. I found that only having air inside the box is leading the transient simulation to "inflate" the box at the start of...

Thanks. I see how you set this up. I've started a transient run with a blow to the top of the guitar saddle in my model, which interestingly is exactly how one recovers the modes with microphone and an FFT analysis on a real instrument. I'm running a simulation at time steps of 0.0001, or 10k Hz, wh...

Thanks Kevin, Looking at the case you did, this is a weakly coupled solution, yes? I ask because, with the strongly coupled solution on my guitar test case, I do see a shift in frequencies in the structure by shifting the density of the fluid. Without the fluid coupling, the top of the guitar's firs...

Thanks Kevin, I will look at both of those this evening. I'm actually trying to study a number of questions here. It might help to give a bit more context. Ultimately, I'm working on understanding the effects of structural choices in soundboard design for guitars. There are number of effects I'm int...

A bit more exploration on this one. First off, I did a bit of reading, I found a number of papers on solving joint fluid structure eigen value problems, which all seemed to indicate that some kind of more complex approach would be needed than simply applying an Eigenvalue solver over the joint block...

I managed to do one more test before I have to head off to work. I modified the solver to do Eigen Analysis of the structure and fluid independently to see what kind of strutures I should be expecting for the modes. I get modes as follows: WaveSolver: Solving the compressional pressure wave WaveSolv...