Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Dimension check in Sound wave equation - Coupling Acoustic with Structural Mechanics
Posted Jun 9, 2017, 6:57 a.m. EDT 1 Reply
Please login with a confirmed email address before reporting spam
Dear all
In acoustic module's user's guide page 119 equation (3-3) the following equation is introduced to desribe the acoustic waves:
[1/(ro)(c)][d2P/dt2]+Nabla[(-1/ro) (Nabla(P)-qd)]=Qm
where the Qm and qd are the monopole and dipole source respectively. The unit of Qm is [1/s2] and for qd is [N/m3]. In the recent COMSOL webinar on acoustics, I asked that how does the coupling works between structural mechanics and the acoustic module and I'm answered that:
"The coupling itself actually enters through the surface acceleration of the solid, which acts as a source of acoustic radiation in the same way as a Normal Acceleration condition in the acoustics interfaces in COMSOL Multiphysics."
Now my question is about the dimensions of the above equation when the acceleration [m/s2] of the solid body is used as a source. I could not find out how the dimensions match in the above equation.
I would appreciate if somebody can explain this to me.
Best regards
Hamid
In acoustic module's user's guide page 119 equation (3-3) the following equation is introduced to desribe the acoustic waves:
[1/(ro)(c)][d2P/dt2]+Nabla[(-1/ro) (Nabla(P)-qd)]=Qm
where the Qm and qd are the monopole and dipole source respectively. The unit of Qm is [1/s2] and for qd is [N/m3]. In the recent COMSOL webinar on acoustics, I asked that how does the coupling works between structural mechanics and the acoustic module and I'm answered that:
"The coupling itself actually enters through the surface acceleration of the solid, which acts as a source of acoustic radiation in the same way as a Normal Acceleration condition in the acoustics interfaces in COMSOL Multiphysics."
Now my question is about the dimensions of the above equation when the acceleration [m/s2] of the solid body is used as a source. I could not find out how the dimensions match in the above equation.
I would appreciate if somebody can explain this to me.
Best regards
Hamid
1 Reply Last Post Jun 9, 2017, 8:26 a.m. EDT
Please login with a confirmed email address before reporting spam
Posted:
8 years ago
Updated:
8 years ago
Apparently, I have to multiply the vibration acceleration from the plate into the density of the medium in which the acoustic wave propagate. But anybody knows why we should take the acceleration, not the velocity or something else? I'm looking for a physical explanation.