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Posted:
1 decade ago
Jan 13, 2012, 12:33 p.m. EST
Any ideas anyone?
I thought it might be nice to have a bit more discussion about the transient analysis on structural interaction.
Any comments would be really welcome.
Thanks,
Rob
Any ideas anyone?
I thought it might be nice to have a bit more discussion about the transient analysis on structural interaction.
Any comments would be really welcome.
Thanks,
Rob
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Posted:
1 decade ago
Jan 13, 2012, 11:02 p.m. EST
Hi,
I can give you suggestions on the different ways to give your source input.
Don't really know how efficient they will be.
1) Using a flow point source you can give your own pulse input .
For eg. S=4*sin(2*pi*100000[Hz]*t)*(t<=0.000001)
In the equation dS/dt is used.Here you have a pulse of frequency 1MHz and time period=1u sec.
2) Using the pressure boundary condition. Since its in 3D you can select a surface as the boundary
and give your pressure pulse as above in the p0 field.
3) Having a background field. Use the cylindrical, plane or spherical wave boundary condition and using the incident pressure field mention the direction of incidence by specifying your propagation constants.
I'm not sure of how effective they are comparatively, just started working on acoustics some time back.
There are couple of models that could help in understanding, a 4.1 version is the hollow cylinder .
I'm not exactly sure if i've helped you.
Regards
Glenston
Hi,
I can give you suggestions on the different ways to give your source input.
Don't really know how efficient they will be.
1) Using a flow point source you can give your own pulse input .
For eg. S=4*sin(2*pi*100000[Hz]*t)*(t
Ivar KJELBERG
COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted:
1 decade ago
Jan 14, 2012, 4:04 a.m. EST
Hi
I do not have acoustics, unfortunately, but as general remark, your pulse 1) is not quite differentiable so you might have some solver issues, you could multiply it by a pulse operator to smoothen it, or try a 1+cos() over a period, or a gaussian type smoothing
--
Good luck
Ivar
Hi
I do not have acoustics, unfortunately, but as general remark, your pulse 1) is not quite differentiable so you might have some solver issues, you could multiply it by a pulse operator to smoothen it, or try a 1+cos() over a period, or a gaussian type smoothing
--
Good luck
Ivar
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Posted:
1 decade ago
Jan 14, 2012, 5:23 a.m. EST
Thank you both for your replies!
I am going away for the weekend and will be away from Comsol for a few days, but I am very much looking forward to trying these out.
Thanks again, I will upload some models which I find to be handy.
Again, thank you
Rob
Thank you both for your replies!
I am going away for the weekend and will be away from Comsol for a few days, but I am very much looking forward to trying these out.
Thanks again, I will upload some models which I find to be handy.
Again, thank you
Rob
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Posted:
1 decade ago
Jan 16, 2012, 5:44 a.m. EST
Hello fellow Comsol-ers!
After a nice weekend of relaxing I am again ready to pull my hair out!
Thank you Glenston and Ivar. Very happy to start a discussion on the topic.
I have a few follow up comments...
Glenston, thank you for your three suggestions. I think your first is the most suitable for my problem.
Ivar, I am not sure what you mean by "is not quite differentiable" but I do believe I have come into some solver issues you mentioned.
I am not sure how you apply smoothing but shall have a read of it now.
Again, thank you both. I will play with these models more and let you know what I find.
Rob
ps, Glenston thank you especially for the equation, it will come in very useful.
Hello fellow Comsol-ers!
After a nice weekend of relaxing I am again ready to pull my hair out!
Thank you Glenston and Ivar. Very happy to start a discussion on the topic.
I have a few follow up comments...
Glenston, thank you for your three suggestions. I think your first is the most suitable for my problem.
Ivar, I am not sure what you mean by "is not quite differentiable" but I do believe I have come into some solver issues you mentioned.
I am not sure how you apply smoothing but shall have a read of it now.
Again, thank you both. I will play with these models more and let you know what I find.
Rob
ps, Glenston thank you especially for the equation, it will come in very useful.
Ivar KJELBERG
COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted:
1 decade ago
Jan 16, 2012, 10:19 a.m. EST
Hi
it's the general issue with i.e. time solving and functions that turn on /off as Dirac pulses, at the transition you have two different derivatives, and this is a headache for the solver. If you use the rect or step or pulse function of COMSOL V4 you will see these have a Heaviside type turn on/off transition that has at least one valid derivative, so the solver can exercise its "step and through" process
--
Good luck
Ivar
Hi
it's the general issue with i.e. time solving and functions that turn on /off as Dirac pulses, at the transition you have two different derivatives, and this is a headache for the solver. If you use the rect or step or pulse function of COMSOL V4 you will see these have a Heaviside type turn on/off transition that has at least one valid derivative, so the solver can exercise its "step and through" process
--
Good luck
Ivar
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Posted:
1 decade ago
Jan 16, 2012, 11:03 a.m. EST
Thank you Ivar,
I see what you are referring to, my hope is to see how the model deviates from experiment and to see if there are solver issues. My hope is that there are none!
Also, for those who find this thread on the forum please have a look here...
www.comsol.de/community/exchange/191/
Its a model I have created to encapsulate what I have learned!
Rob
Thank you Ivar,
I see what you are referring to, my hope is to see how the model deviates from experiment and to see if there are solver issues. My hope is that there are none!
Also, for those who find this thread on the forum please have a look here...
http://www.comsol.de/community/exchange/191/
Its a model I have created to encapsulate what I have learned!
Rob
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Posted:
1 decade ago
Jan 16, 2012, 12:26 p.m. EST
Hi Robert,
Can you please upload a 4.2 version of the model.
Its not opening on the 4.2 so i'm assuming that its the 4.2a model.
Regards
Glenston
Hi Robert,
Can you please upload a 4.2 version of the model.
Its not opening on the 4.2 so i'm assuming that its the 4.2a model.
Regards
Glenston
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Posted:
1 decade ago
Jan 17, 2012, 6:15 a.m. EST
Hi Glenston,
Thanks for spotting that! I have now updated the model in the model exchange with a 4.2 version.
(I did not know how to save as a 4.2 file in 4.2a so I created a new one)
Rob
Hi Glenston,
Thanks for spotting that! I have now updated the model in the model exchange with a 4.2 version.
(I did not know how to save as a 4.2 file in 4.2a so I created a new one)
Rob
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Posted:
1 decade ago
Jan 17, 2012, 6:15 a.m. EST
Hi Glenston,
Thanks for spotting that! I have now updated the model in the model exchange with a 4.2 version.
(I did not know how to save as a 4.2 file in 4.2a so I created a new one)
Rob
Hi Glenston,
Thanks for spotting that! I have now updated the model in the model exchange with a 4.2 version.
(I did not know how to save as a 4.2 file in 4.2a so I created a new one)
Rob
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Posted:
1 decade ago
Feb 8, 2012, 3:18 p.m. EST
Hi Rob,
By reviewing your guys previous discussion, I think I am trying to do sth similar. I would like generate a transient pulse to see the pressure distribution in a domain and some of the interaction with silicone which is in my environment. I am kind of stuck here by finding a similar plate source. All comsol give are the point or edge source. How can I have a circular boundary source?
Could you offer some ideas?
For your project, did you do the transient acoustic interaction physics?
By the way, I am trying to download your files from comsol exchange, however, my 4.1 version cant open any of them.
Do you happen to have 4.1 version?
Thanks a lot.
Best
Xu
Hi Rob,
By reviewing your guys previous discussion, I think I am trying to do sth similar. I would like generate a transient pulse to see the pressure distribution in a domain and some of the interaction with silicone which is in my environment. I am kind of stuck here by finding a similar plate source. All comsol give are the point or edge source. How can I have a circular boundary source?
Could you offer some ideas?
For your project, did you do the transient acoustic interaction physics?
By the way, I am trying to download your files from comsol exchange, however, my 4.1 version cant open any of them.
Do you happen to have 4.1 version?
Thanks a lot.
Best
Xu
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Posted:
9 years ago
Oct 15, 2015, 3:41 p.m. EDT
Hi Robert,
I am facing a problem similar to your.
I am simulating a horn response.
I am trying use a curve, based from excel data, as Incident Pressure Field.
I got the data from excel and it generated a graphic that I can see in the results, but I am not capable to use it exciting my model.
Do you have a suggestion to solve my problem?
Thanks,
Best regards,
Hi Robert,
I am facing a problem similar to your.
I am simulating a horn response.
I am trying use a curve, based from excel data, as Incident Pressure Field.
I got the data from excel and it generated a graphic that I can see in the results, but I am not capable to use it exciting my model.
Do you have a suggestion to solve my problem?
Thanks,
Best regards,