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.
Laser - Moving a Heat Boundary
Posted 11 feb 2011, 22:35 GMT-5 23 Replies
Please login with a confirmed email address before reporting spam
Hi everybody,
I'm new to COMSOL 4.0a and currently trying to move a heat source over a simple plate. Stuck, on what I expect to be a simple model. I looked at the 699 model, but assumption (point source) are not correct for my modeling.
Here is where I am:
- I have a plate on which is a small block (representing the laser beam) : Heat Flux condition is set on his upper face.
- I'm trying to move the source over the plate on straight line ( like Bianco and Manca did. )
To achieve this I used the Translational Motion under Heat Transfer in Solids. Based on the built-in disc brake model.
So the heat flow is acting like if the heat source is moving (directionnal flow), but the heat source stay at its initial position ! So I have a correct heat flow, virtually moving, but that stay at the same place on the plate.
How can I proceed to move the block (laser beam) on the plate ?
Thank you in advance for the tips !
Regards,
I'm new to COMSOL 4.0a and currently trying to move a heat source over a simple plate. Stuck, on what I expect to be a simple model. I looked at the 699 model, but assumption (point source) are not correct for my modeling.
Here is where I am:
- I have a plate on which is a small block (representing the laser beam) : Heat Flux condition is set on his upper face.
- I'm trying to move the source over the plate on straight line ( like Bianco and Manca did. )
To achieve this I used the Translational Motion under Heat Transfer in Solids. Based on the built-in disc brake model.
So the heat flow is acting like if the heat source is moving (directionnal flow), but the heat source stay at its initial position ! So I have a correct heat flow, virtually moving, but that stay at the same place on the plate.
How can I proceed to move the block (laser beam) on the plate ?
Thank you in advance for the tips !
Regards,
23 Replies Last Post 11 nov 2011, 08:02 GMT-5
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Update on this:
I'm now using a parameter sweep (under study) to move the geometric position of the heat source. Effectively move the laser beam, but the heat flow in the workpiece seem to be independent from the precedent positions travelled by the laser beam: no heat flow trail.
I'm now using a parameter sweep (under study) to move the geometric position of the heat source. Effectively move the laser beam, but the heat flow in the workpiece seem to be independent from the precedent positions travelled by the laser beam: no heat flow trail.
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Ok, it is now working.
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
you have another example here too, I made a cylindrical coordinate reference with two variables X0,Y0 defining the centre of the sys2 coordinate (Lissajou figures depending on the time, see Definition Variables). Then I define a exponential beam diameter as an analytical function. Use the time stepping solver and set enough steps AND use the STRICT time stepping (otherwise the default settings of the solver will skip many points ;)
Do not forget to use a mesh density small enough to resolve the spot (3-5 elements per spor radius at least).
Then an issue to meditate: heat power densities (these are defined as volumetric densities and in 2D COMSOL assumes a 1[m] thick volume) but what happens between the time steps ? (nothing in fact) so this simulates a pulsed source with a time integrated power density at the time analysis.
Next fun is to apply it to a 3D with a true heat source surface density applied
it's a 4.1.0.154 model
--
Good luck
Ivar
you have another example here too, I made a cylindrical coordinate reference with two variables X0,Y0 defining the centre of the sys2 coordinate (Lissajou figures depending on the time, see Definition Variables). Then I define a exponential beam diameter as an analytical function. Use the time stepping solver and set enough steps AND use the STRICT time stepping (otherwise the default settings of the solver will skip many points ;)
Do not forget to use a mesh density small enough to resolve the spot (3-5 elements per spor radius at least).
Then an issue to meditate: heat power densities (these are defined as volumetric densities and in 2D COMSOL assumes a 1[m] thick volume) but what happens between the time steps ? (nothing in fact) so this simulates a pulsed source with a time integrated power density at the time analysis.
Next fun is to apply it to a 3D with a true heat source surface density applied
it's a 4.1.0.154 model
--
Good luck
Ivar
Attachments:
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Thank you very much Ivar,
I'll try to move to 4.1 and see your model !
Regards,
Gabriel
I'll try to move to 4.1 and see your model !
Regards,
Gabriel
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi
I see what you have written in previous steps is exactly what I am working on now. and now I am in this step and could not find how to make the model dependent to precedent steps.
could you pleasee help me.
are you saying using parametric sweep we can make the model to have dependency to the previous step.? that is awesome for me..please help me with this.
I see what you have written in previous steps is exactly what I am working on now. and now I am in this step and could not find how to make the model dependent to precedent steps.
could you pleasee help me.
are you saying using parametric sweep we can make the model to have dependency to the previous step.? that is awesome for me..please help me with this.
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi Gabriel
I appreciate if you let me know about this problem which is making me crazy !
thanks
naveedasadee@gmail.com
I appreciate if you let me know about this problem which is making me crazy !
thanks
naveedasadee@gmail.com
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hello Navid,
you need to move the parametric value from results as well as the solved time.
It is not really 'automatic', you need to do this manually for each solution.
you need to move the parametric value from results as well as the solved time.
It is not really 'automatic', you need to do this manually for each solution.
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi Gabriel
Thanks for your comment. I am trying to go with your comment. my problem is a 3D and so I have to do the simulation for one step for example a parametric sweep from 3mm to 3.1mm in a time dependence solution like from 0 to 0.1 sec and then go to results and change them from solutions. is it what is should look for?
can you give me some hints for that please. like in which part of results... because first if we do the simulation for a range of parametric sweep and range of time then results are already there and how are they going to be changed?
I know it is a lot of questions please give me some hints.
thanks
Thanks for your comment. I am trying to go with your comment. my problem is a 3D and so I have to do the simulation for one step for example a parametric sweep from 3mm to 3.1mm in a time dependence solution like from 0 to 0.1 sec and then go to results and change them from solutions. is it what is should look for?
can you give me some hints for that please. like in which part of results... because first if we do the simulation for a range of parametric sweep and range of time then results are already there and how are they going to be changed?
I know it is a lot of questions please give me some hints.
thanks
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
hi Gabriel
I tried to do what you said but when you run the simulation in different sweeps in parametric sweep it has results for each sweep as default which is not temperature trial. could you please explain how to change parametric sweep and time?
do you mean by this method, COMSOL solves the problem for one step, then if we change the parametric sweep from results (which I could not find how to do it) then COMSOL does the new simulation over the results of previous step and adds the new temperature contour to the last one (which is my goal to achieve :( ).
Is this problem have to be done by this method? can we do this by moving mesh or Deformed Geometry? I tried them both but when the hot box moves it has no changes on the bottom box! and looks like there is no conduction between boxes.
Please help me!
Navid
I tried to do what you said but when you run the simulation in different sweeps in parametric sweep it has results for each sweep as default which is not temperature trial. could you please explain how to change parametric sweep and time?
do you mean by this method, COMSOL solves the problem for one step, then if we change the parametric sweep from results (which I could not find how to do it) then COMSOL does the new simulation over the results of previous step and adds the new temperature contour to the last one (which is my goal to achieve :( ).
Is this problem have to be done by this method? can we do this by moving mesh or Deformed Geometry? I tried them both but when the hot box moves it has no changes on the bottom box! and looks like there is no conduction between boxes.
Please help me!
Navid
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi Gabriel
do we have to change the parametric sweep from job configuration in the study part.
I did it and also unchecked the tick mark near clear previous in the output part of solver. but again there is no temperature trial :((
i appreciate advices.
Navid
do we have to change the parametric sweep from job configuration in the study part.
I did it and also unchecked the tick mark near clear previous in the output part of solver. but again there is no temperature trial :((
i appreciate advices.
Navid
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hello Navid,
you change the parametric sweep and time by setting them in a Time-Dependant Solver. Yes, parametric will generate a solution for each time step, for each parametric values. ie: if you have a step time of 5 seconds, with a parametric sweep giving 4 positions, you will have 20 solutions.
In the results, you need to choose the parametric value on the solution (under Data Sets), then choose the right time value corresponding to this position on the plot setting.
I'm about to finish an article using this method, which expound exact matching with results from other sudies in conduction limited case.
I'lll keep you in touch with that.
Yes, all road lead to Rome. See the model sent by Ivar for the same problem.
Gabriel
you change the parametric sweep and time by setting them in a Time-Dependant Solver. Yes, parametric will generate a solution for each time step, for each parametric values. ie: if you have a step time of 5 seconds, with a parametric sweep giving 4 positions, you will have 20 solutions.
In the results, you need to choose the parametric value on the solution (under Data Sets), then choose the right time value corresponding to this position on the plot setting.
I'm about to finish an article using this method, which expound exact matching with results from other sudies in conduction limited case.
I'lll keep you in touch with that.
Yes, all road lead to Rome. See the model sent by Ivar for the same problem.
Gabriel
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hello Gabriel
I think I did the same thing but what I have in results is just a box (as my heat source) in 3 positions and in each position it acts for 5 seconds in each case for example from 200 to 300 degree of Celsius. but the other box which is in contact with it under it is effected completely independent of the last step :( . I need the temperature contour on the bottom box to keep the results of each of the three steps :(.
what is wrong with me, I do the same :( but no temperature trial.
maybe I have not said my problem clearly because of my english problem, but I think we had same problem. I have attached a picture please take a look at it. I want the upper box moves along the bottom one and in each step stays about 0.5 second, the box has a constant temperature (which I should change for next step and make it caused to effects from the cold bottom box) . so using the parametric sweep makes independent temperature contour in each step :( even when I change it from results. It looks like we can not add temperature results from previous step to the new step and go through it :(
I appreciate your helps a lot.
sincerely
I think I did the same thing but what I have in results is just a box (as my heat source) in 3 positions and in each position it acts for 5 seconds in each case for example from 200 to 300 degree of Celsius. but the other box which is in contact with it under it is effected completely independent of the last step :( . I need the temperature contour on the bottom box to keep the results of each of the three steps :(.
what is wrong with me, I do the same :( but no temperature trial.
maybe I have not said my problem clearly because of my english problem, but I think we had same problem. I have attached a picture please take a look at it. I want the upper box moves along the bottom one and in each step stays about 0.5 second, the box has a constant temperature (which I should change for next step and make it caused to effects from the cold bottom box) . so using the parametric sweep makes independent temperature contour in each step :( even when I change it from results. It looks like we can not add temperature results from previous step to the new step and go through it :(
I appreciate your helps a lot.
sincerely
Attachments:
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi Navid,
Effectively, your problem seem to be independent from time laps.
Are you using a Time-Dependant solver ?
Have you tried to use Translational Motion for the entire model ?
Effectively, your problem seem to be independent from time laps.
Are you using a Time-Dependant solver ?
Have you tried to use Translational Motion for the entire model ?
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
yes it is time dependent. but you can not change parametric sweep and time both together. so in each step or location of melt COMSOL does the time dependent analysis so just looks like heat source is stayed for long time. then for next location of heat box COMSOL again does the time deponent analysis regardless of previous step.
I actually have some other terms in the bottom box so I can not use translational motion :(.
could you please take a look at COMSOL file. it is for 4.0
I actually have some other terms in the bottom box so I can not use translational motion :(.
could you please take a look at COMSOL file. it is for 4.0
Attachments:
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Gabriel
It is going to be like melt which flows over a mold so melt is replaced with that hot box. as it goes further it should consider the steps before it. dependent steps are simply done but relating these steps together and find out something which looks like the transitional motion of heat source. I can not use that becaus eI have some cylinders in the bottom box and using translational motion the heat flux behind those cylinders would not be like when the hot box is going over the bottom box.
I appreciate your notes if you know how to do this problem :(
Thanks
It is going to be like melt which flows over a mold so melt is replaced with that hot box. as it goes further it should consider the steps before it. dependent steps are simply done but relating these steps together and find out something which looks like the transitional motion of heat source. I can not use that becaus eI have some cylinders in the bottom box and using translational motion the heat flux behind those cylinders would not be like when the hot box is going over the bottom box.
I appreciate your notes if you know how to do this problem :(
Thanks
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Navid,
I'have looked at your model. I does not seem to work tough....
Why don't you slide the upper bar over the bottom one rather than extending it ?
Try to use a finer mesh and use a more extensive time to be shure it doest not work; even if aluminium is highly conductive, 0.1 sec is quite short to diffuse heat.
Regards,
I'have looked at your model. I does not seem to work tough....
Why don't you slide the upper bar over the bottom one rather than extending it ?
Try to use a finer mesh and use a more extensive time to be shure it doest not work; even if aluminium is highly conductive, 0.1 sec is quite short to diffuse heat.
Regards,
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
hi Gabriel
thanks for your answers. I used the deformed geometry for sliding too (is that the right way?) and I again had the same problem it was 1 second not 0.1 anyhow I extended to 4 seconds in the tmie dependent range and I again did not see change. so the upper box moves forward but temperature contour is just changes for the first step .:(
I am really confused:(
Gabriel, it looks like as I define the temperature of the upper box it just stays there!! please take a look at the picture!
Gabriel, I think my problem is that conduction between two boxes is not defined. just the common surface between upper and lower box is defined as temperature. so these two boxes had condition between each other then I should had temperature contour in further steps, is there a option to define condition between objects in COMSOL? I have not seen that!
Thanks
thanks for your answers. I used the deformed geometry for sliding too (is that the right way?) and I again had the same problem it was 1 second not 0.1 anyhow I extended to 4 seconds in the tmie dependent range and I again did not see change. so the upper box moves forward but temperature contour is just changes for the first step .:(
I am really confused:(
Gabriel, it looks like as I define the temperature of the upper box it just stays there!! please take a look at the picture!
Gabriel, I think my problem is that conduction between two boxes is not defined. just the common surface between upper and lower box is defined as temperature. so these two boxes had condition between each other then I should had temperature contour in further steps, is there a option to define condition between objects in COMSOL? I have not seen that!
Thanks
Attachments:
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Gabriel are you using version 4.1 ? I am using 4.0. Is it doable in it?
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
I work with both.
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Try to intersect two geometries: your answer about boundaries will be clear. It depends on which part of the workpiece you defined heat transfer (Edge, Surface, Volume).
Try to move a single workpiece, not to change its geometry.
Maybe start a new Topic ?
Courage !
Try to move a single workpiece, not to change its geometry.
Maybe start a new Topic ?
Courage !
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
thank you again Gabriel
I used moving mesh too but it did not worked. so can you give me help which tool should I work with for this goal?
in the 3D model when you want to define temperature or heat flux it just let to select surfaces,right? can you give me hint which tools in COMSOL should I work with? I am new and it is really vast.
Thanks
I used moving mesh too but it did not worked. so can you give me help which tool should I work with for this goal?
in the 3D model when you want to define temperature or heat flux it just let to select surfaces,right? can you give me hint which tools in COMSOL should I work with? I am new and it is really vast.
Thanks
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hello Gabriel
I am making a very simple 2d model containing two rectangles. I am using the smaller rectangle as moving heat source. But, in my solution the smaller block is not moving from its initial position.
Thanks
I am making a very simple 2d model containing two rectangles. I am using the smaller rectangle as moving heat source. But, in my solution the smaller block is not moving from its initial position.
Thanks
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hello Ashish,
you'r right: by applying a Translation motion, your are inducing a movement to the heat flow only, not on the geometry.
One way is to achieve a ''moving'' geometry is to Parametrize its position. This worked well for me and this have been experimentally tested founding a good accuracy between simulations and experiments.
Another could use moving mesh (ALE). I think Navid (in the same thread) have successfully implemented this approach in his models.
Regards,
you'r right: by applying a Translation motion, your are inducing a movement to the heat flow only, not on the geometry.
One way is to achieve a ''moving'' geometry is to Parametrize its position. This worked well for me and this have been experimentally tested founding a good accuracy between simulations and experiments.
Another could use moving mesh (ALE). I think Navid (in the same thread) have successfully implemented this approach in his models.
Regards,