# How to model a moving heat source?

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 March 12, 2009, 13:56 How to model a moving heat source? #1 James Guest   Posts: n/a How can FLOW-3D be used to model a moving heat source? The user manual only tells how to model uniform or localized heat sources. But what if the location of a heat source changes during a process? Thanks!

 March 12, 2009, 14:06 Re: How to model a moving heat source? #2 HC Guest   Posts: n/a is the heat source inside some solid object? if so, you may try create an extra moving solid object and use it as the heat source.

 March 12, 2009, 14:21 Re: How to model a moving heat source? #3 James Guest   Posts: n/a It is on the surface of a solid object. For example, a moving laser beam is irradiated on the surface of a metal part.

 March 12, 2009, 14:28 Re: How to model a moving heat source? #4 HC Guest   Posts: n/a I think you can try creating a moving object and specify the heat source with density*specific heat equal to 0. that way, the heat source value becomes the heat flux at the component's surface.

 March 12, 2009, 15:54 Re: How to model a moving heat source? #5 James Guest   Posts: n/a Thank you! In this way, how can I apply the heat flux only at a portion of the component's surface? I mean, the heat source is not applied to the whole surface, just to a circular region of the surface.

 March 12, 2009, 17:11 Re: How to model a moving heat source? #6 HC Guest   Posts: n/a One way is to create another moving component that wraps around the heat source and only have that circular region facing outwards. This method might not be appropriate for the cases you are simulating, as you do not want the new moving components to affect the heat transfer/fluid flow. May I ask what kind of case you are trying to simulate?

 March 12, 2009, 21:58 Re: How to model a moving heat source? #7 James Guest   Posts: n/a I am simulating laser coating.

 March 13, 2009, 09:38 Re: How to model a moving heat source? #8 HC Guest   Posts: n/a so how does the laser beam move? does it just moves along a flat surface? if it does, you can just try what we have suggested and you dont need to create another wrapping component as the other area on the moving heat source component will not be in contact with the material. you also need to specify free-slip on the moving component as the laser beam would not have any force acting on the material. Anyways, basically you need to make sure no setup in the simulation would contradict the basic process in laser coating. if it does, please give more details on the process, or you want to think about customization. jscsgh likes this.

 March 13, 2009, 17:00 Re: How to model a moving heat source? #9 James Guest   Posts: n/a My application is like this: a laser beam passes over the top surface of the base material to induce local melting.The effect is that it brings a heat flux on the surface. Accompanying the laser beam is a droplet source of coating material that strike the surface and provide the extra material. So during the process, the surface of the base material is not flat because it is coated. It is something like laser welding. The difficulty of modeling is that the heat flux is not on the whole surface at a specific moment (just a circular spot) and moves along the surface. If I use customization, how should I do? Thank you!

 March 16, 2009, 12:52 #10 Member   Join Date: Mar 2009 Posts: 40 Rep Power: 17 so do the laser beam and droplet source happen to be at the same location at that time? if not and laser beam melts the FLAT base material first before a droplet is placed on the surface, you can still use that technique to mimic the process. the customization you could try is to modify heatfl.F. Basically you need to keep track of the i/j/k index of the cells where the laser beam is projected on, and to specify the heat source in the subroutine. It is kind of different as it is thermal energy per unit mass instead of heat flux at the surface, but it might be ok if the cells are fine enough.

 March 17, 2009, 11:49 Re:How to model a moving heat source #11 New Member   James Zhong Join Date: Mar 2009 Posts: 25 Rep Power: 17 Thank you for your reply! Yes, the laser beam and droplet source are always at the same location. But before laser beam melts the FLAT base material, probabily the powder particles will be blown off. I don't need to model this. In my simulation, I let the droplets fall onto the base material only after a molten pool has formed. Could you please say again what "that technique to mimic the process" is? Because you mentioned several methods, I am a little bit confused. For the customization, is heatfl1 an array with subscripts i,j,k or a variable? Can I use other variables like t, xi(i),yj(j) and zk(k) in this subroutine? Another related question is: how does Flow-3D distingush among a void cell, a fluid cell and a solid cell? Thank you!

January 7, 2015, 21:59
#12
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Guangxi
Join Date: Sep 2014
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Quote:
 Originally Posted by H.C so do the laser beam and droplet source happen to be at the same location at that time? if not and laser beam melts the FLAT base material first before a droplet is placed on the surface, you can still use that technique to mimic the process. the customization you could try is to modify heatfl.F. Basically you need to keep track of the i/j/k index of the cells where the laser beam is projected on, and to specify the heat source in the subroutine. It is kind of different as it is thermal energy per unit mass instead of heat flux at the surface, but it might be ok if the cells are fine enough.
Hi H.C,

I'm doing the same thing as you have done years ago, since heatfl is power source per unit mass,when I define a gauss plane heat source, how can I convert power rate (unit: W) to power source per unit mass? In other words, when the power rate equal 1w, then heatfl= ?, thank you~

Last edited by boy; January 9, 2015 at 02:11.

December 5, 2019, 21:16
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Zeqi Hu
Join Date: Dec 2016
Location: Wuhan City, Hubei Province, China
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Quote:
 Originally Posted by HC ;93324 I think you can try creating a moving object and specify the heat source with density*specific heat equal to 0. that way, the heat source value becomes the heat flux at the component's surface.

For the welding simulation, I want to apply a Gaussian heat flux on the free surface cells. I modified the rhoe(ijk) density*specific of the free surface cells in the qsadd.F90 subrutine, the temperature could increased normally at first seconds, but when the temperature exceeded the melting point, the solver run into an error, what's wrong with it? Thank you.

 March 2, 2020, 15:31 #14 Senior Member   thunde47 Join Date: Dec 2015 Location: India, USA Posts: 128 Blog Entries: 1 Rep Power: 10 You guys can explore FLOW-3D WELD and FLOW-3D DEM for different additive manufacturing simulations. Contact info@flow3d.com for more details.

 June 29, 2020, 08:46 Moving Runner #15 New Member   James Spencer Join Date: Apr 2020 Posts: 1 Rep Power: 0 I'm trying to add a metal input where once it hits a history probe the metal input lifts to the height of mould. the events trigger see the probe but does not do anything. please can you advise on work around?