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acoustic wave out of laser pulse
Posted Mar 22, 2010, 10:24 a.m. EDT 3 Replies
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Hello,
the subject seems to be huge, but my question is short:
How can I implement a intensity or energy at a boundary as a source for an acoustic wave?
Because in the acoustic physics mode in the boundary settings it has to be a pressure in Pascal.
Do I have to claculate a pressure out of my energy impulse (if yes, how to do so?) or is it possible to implement the pulse energy in Joule, for example, as a source for the wave?
Thanks for your help!
Best regards,
Christoph Mannal
3 Replies Last Post Mar 22, 2010, 1:10 p.m. EDT
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Posted:
2 decades ago
Yes you need to calculate a pressure pulse.
and this has nothing to do with comsol but everything about the physic of the coupling between the laser and the target [ HUGE subject indeed :-) ]and also of the accuracy you need for your modeling work [ simple formula existthat will provide with a solution but not very accurate... .
This is something you need to find for yourself or wih expert of the kind of effect you want/need to model
jf
and this has nothing to do with comsol but everything about the physic of the coupling between the laser and the target [ HUGE subject indeed :-) ]and also of the accuracy you need for your modeling work [ simple formula existthat will provide with a solution but not very accurate... .
This is something you need to find for yourself or wih expert of the kind of effect you want/need to model
jf
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Posted:
2 decades ago
Thanks for the quick answer.I am trying to get a solution.It do not have to be accurate.Which simple formula do you mean?
Thanks again,
C.Mannal
Thanks again,
C.Mannal
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Posted:
2 decades ago
well I dont know how to put it....
but it depends of your problem [ nature of your target, nature of the laser..
but usually you cannot do numerical simulation of a physic you dont know or dont master
Comsol like any other fem package is not a magic wand.
this is just a tool and you need to know what to do with it.
this forum is not , I thik about laser matter interaction not am I an expert on this .
but assuming your target is solid and your pulse brief compared to the time "deposition thickness/soundwave of the target" you can use the Gruneisen "gamma" coefficient that give P=Gamma rho E. rho solid density of the target e deposited total energy to get an estimate of the peak pressure generated you then need to devise a time profile using impulse conservation and other physical feature of your targets.... again a complicated subject...
and again this is a crude formula valid in narrow range of conditions but often usefull to " debunk a problm or check more sophisticated models..
jf
but it depends of your problem [ nature of your target, nature of the laser..
but usually you cannot do numerical simulation of a physic you dont know or dont master
Comsol like any other fem package is not a magic wand.
this is just a tool and you need to know what to do with it.
this forum is not , I thik about laser matter interaction not am I an expert on this .
but assuming your target is solid and your pulse brief compared to the time "deposition thickness/soundwave of the target" you can use the Gruneisen "gamma" coefficient that give P=Gamma rho E. rho solid density of the target e deposited total energy to get an estimate of the peak pressure generated you then need to devise a time profile using impulse conservation and other physical feature of your targets.... again a complicated subject...
and again this is a crude formula valid in narrow range of conditions but often usefull to " debunk a problm or check more sophisticated models..
jf