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Using a Gaussian Pulse

Posted 26 apr 2013, 04:47 GMT-4 Wave Optics, Heat Transfer & Phase Change 13 Replies

Samy Abdallah
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Hi everyone,

I'm actuallay working on a modeling of a laser pulse which is heating a front of a material in order to determinate the diffusivity, my current issue is that i would like to model my heat source by a pulsian gauss but i don't really know how to integrate the fact that the heat source is a gaussian pulse type.
Thank you for reading this topic and i hope some of you could answer to my question.
Have a nice day !

Cordially,
Samy
13 Replies Last Post 5 gen 2016, 08:31 GMT-5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 26 apr 2013, 05:28 GMT-4
Hi

there are some examples already on the FORUM, perhaps a year old by now ;)

You need to dig into the COMSOL help and search for Gaussian pulse to find the full formula with the normalisation used, then define your Gaussian function and include it into an analytical one such that you get the desired amplitude or integral value to fit your desired height or area / energy / power

--
Good luck
Ivar
Hi there are some examples already on the FORUM, perhaps a year old by now ;) You need to dig into the COMSOL help and search for Gaussian pulse to find the full formula with the normalisation used, then define your Gaussian function and include it into an analytical one such that you get the desired amplitude or integral value to fit your desired height or area / energy / power -- Good luck Ivar
Samy Abdallah
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Posted: 1 decade ago 30 apr 2013, 08:14 GMT-4
Hey Ivar,

Thank your for your advice but unfortunately i couldn't find anything relevant about the normalisation of the gaussian, that you were talking in your thread, there's something that i didn't say in my previous post is that i want to modelize it in 3D, I don't know if it will change something and at least i've a question about the definition of the gaussian, the x-axis depend on time or a distance ?

Thank you for your quick answer-making !

Cordially
Samy
Hey Ivar, Thank your for your advice but unfortunately i couldn't find anything relevant about the normalisation of the gaussian, that you were talking in your thread, there's something that i didn't say in my previous post is that i want to modelize it in 3D, I don't know if it will change something and at least i've a question about the definition of the gaussian, the x-axis depend on time or a distance ? Thank you for your quick answer-making ! Cordially Samy
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 30 apr 2013, 14:14 GMT-4
Hi
then you need to search a bit more in the help, the definition of the gaussian is in there but not on the first page about gaussian that appear, not sure why.

if you have a 2D gaussian for a 3Dmodel you need to define one for X and one for Y (or use the same one twice)

--
Good luck
Ivar
Hi then you need to search a bit more in the help, the definition of the gaussian is in there but not on the first page about gaussian that appear, not sure why. if you have a 2D gaussian for a 3Dmodel you need to define one for X and one for Y (or use the same one twice) -- Good luck Ivar
Samy Abdallah
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Posted: 1 decade ago 3 mag 2013, 08:51 GMT-4
Hi,

Sorry to bother you again Ivar but i really can't find the expression of my gaussian, I would really appreciate if you could be more specific about should I search on the forum.

Best regards
Hi, Sorry to bother you again Ivar but i really can't find the expression of my gaussian, I would really appreciate if you could be more specific about should I search on the forum. Best regards
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 3 mag 2013, 11:04 GMT-4
Hi

looks like this ;)
v4.3a.161

--
Good luck
Ivar
Hi looks like this ;) v4.3a.161 -- Good luck Ivar

Attachments:

Samy Abdallah
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Posted: 1 decade ago 13 mag 2013, 07:58 GMT-4
Hi,

Thank you for your screen but i think that i read this page like 20 times and nevertheless i'm not getting any wiser, that's the analytical expression of the gaussian and not the way i should write it (normalisation) on Comsol but nevermind thank you for your time and your help, I hope I'll have my enlightenment moment.

Cordially
Hi, Thank you for your screen but i think that i read this page like 20 times and nevertheless i'm not getting any wiser, that's the analytical expression of the gaussian and not the way i should write it (normalisation) on Comsol but nevermind thank you for your time and your help, I hope I'll have my enlightenment moment. Cordially
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago 13 mag 2013, 09:49 GMT-4
Hi Sam,

Here is a link to a thread describing the Gaussian pulse: www.comsol.com/community/forums/general/thread/31879, in addition to the manual page that Ivar mentioned. The pulse can be in time or space, and if you want it in 2D or 3D you can take the product of Gaussian pulses in each dimension.

I hope this helps.

Nagi Elabbasi
Veryst Engineering
Hi Sam, Here is a link to a thread describing the Gaussian pulse: http://www.comsol.com/community/forums/general/thread/31879, in addition to the manual page that Ivar mentioned. The pulse can be in time or space, and if you want it in 2D or 3D you can take the product of Gaussian pulses in each dimension. I hope this helps. Nagi Elabbasi Veryst Engineering
Samy Abdallah
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Posted: 1 decade ago 14 mag 2013, 05:33 GMT-4
Hi Nagi,

First of, thank you for you help and secondly I've question, my geometry is an half cylinder (3D) and I want to applicate my gaussian pulse in front of my material, should I have an expression like Q(flux)=gp1(x-k*t)*gp2(y-k*t)*gp3(z-k*t) with k the pulse and x,y and z my different direction ? Because when I try with this expression I've message like "Unconsistent unit" and the solver seems failing when I try to solve it.

Thank you for your time

Samy
Hi Nagi, First of, thank you for you help and secondly I've question, my geometry is an half cylinder (3D) and I want to applicate my gaussian pulse in front of my material, should I have an expression like Q(flux)=gp1(x-k*t)*gp2(y-k*t)*gp3(z-k*t) with k the pulse and x,y and z my different direction ? Because when I try with this expression I've message like "Unconsistent unit" and the solver seems failing when I try to solve it. Thank you for your time Samy
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago 14 mag 2013, 10:40 GMT-4
Hi Samy,

The inconsistent units issue is a warning that can be removed by properly setting the units. However, if you did your units calculation correctly outside COMSOL you have nothing to worry about. Something else is probably causing the convergence failure.

Nagi Elabbasi
Veryst Engineering
Hi Samy, The inconsistent units issue is a warning that can be removed by properly setting the units. However, if you did your units calculation correctly outside COMSOL you have nothing to worry about. Something else is probably causing the convergence failure. Nagi Elabbasi Veryst Engineering
Samy Abdallah
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Posted: 1 decade ago 17 mag 2013, 08:26 GMT-4
Hello,

That's me again, I just wanted to know what is the meaning of the "sigma" also call the deviation, in the definition of the gaussian pulse. At first i thought that it was the distance at half height of the gaussian but when I try to change my sigma, I get some strange results so that's why I guess that i didn't get all the ins and outs about the function.

Thank you in advance.

Cordially,

Samy
Hello, That's me again, I just wanted to know what is the meaning of the "sigma" also call the deviation, in the definition of the gaussian pulse. At first i thought that it was the distance at half height of the gaussian but when I try to change my sigma, I get some strange results so that's why I guess that i didn't get all the ins and outs about the function. Thank you in advance. Cordially, Samy
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago 17 mag 2013, 08:30 GMT-4
Sigma is the standard deviation which is a measure of the dispersion or spread of the curve. See this Wikipedia link for a good explanation: en.wikipedia.org/wiki/Standard_deviation
Sigma is the standard deviation which is a measure of the dispersion or spread of the curve. See this Wikipedia link for a good explanation: http://en.wikipedia.org/wiki/Standard_deviation
Letian Wang
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Posted: 1 decade ago 30 ott 2014, 02:07 GMT-4
Hi

As Ivar said, I think you can check out the gallery: www.comsol.com/model/laser-hea...g-a-self-guided-tutorial-12317
also there is a paper: www.comsol.com/paper/download/63243/poulain_paper.pdf

I am also working on laser processing. Nice meeting you!

Letian
Hi As Ivar said, I think you can check out the gallery: www.comsol.com/model/laser-hea...g-a-self-guided-tutorial-12317 also there is a paper: www.comsol.com/paper/download/63243/poulain_paper.pdf I am also working on laser processing. Nice meeting you! Letian
Walter Frei COMSOL Employee

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Posted: 9 years ago 5 gen 2016, 08:31 GMT-5
For the general topic of laser heating as you're describing here, please also see:

www.comsol.com/model/13835

www.comsol.com/blogs/modeling-laser-material-interactions-in-comsol-multiphysics

www.comsol.com/blogs/modeling-laser-material-interactions-with-the-beer-lambert-law

www.comsol.com/blogs/tracking-material-damage-with-the-previous-solution-operator

www.comsol.com/blogs/modeling-a-periodic-heat-load

www.comsol.com/blogs/implementing-simple-temperature-controller-component-coupling
For the general topic of laser heating as you're describing here, please also see: http://www.comsol.com/model/13835 http://www.comsol.com/blogs/modeling-laser-material-interactions-in-comsol-multiphysics http://www.comsol.com/blogs/modeling-laser-material-interactions-with-the-beer-lambert-law http://www.comsol.com/blogs/tracking-material-damage-with-the-previous-solution-operator http://www.comsol.com/blogs/modeling-a-periodic-heat-load http://www.comsol.com/blogs/implementing-simple-temperature-controller-component-coupling

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