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COMSOL+Heat Transfer

  1. Sep 6, 2008 #1
    Hi guys,

    I found this forum by chance. Was wondering if anyone could help out with my problem. I am very new to this COMSOL and I am required to tackle a problem.

    I am required to simulate laser drilling onto a material using comsol to obtain the heat transfer pattern. I have chosen silicon in the drop-down box

    I used the New>FEM>Heat Transfer>Conduction>Transient Analysis.
    I then created a rectangle with 3 sides thermally insulated and the top is having heat flux.

    Under Boundary settings, I need to enter the equation in the Q field as the heat source
    The equation is like this: (10^7) x exponential (-10^3 x X^2) for a time of 2 seconds.

    I keep having syntax errors. How do I put in the equation properly?

  2. jcsd
  3. Sep 6, 2008 #2


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    Hi Skyeagle,

    Comsol syntax is pretty much identical to that of Matlab (well they share plenty of history) ..... so for your equation you might try something like:


    I'm assuming what you're after with the "x" is a cartesian coordinate (or that is how comsol would interpret from the above)? The "t<=2" evaluates as "1" for t <=2 (assuming your t is in seconds) and 0 otherwise (you can do the same thing with a simple "if" - construct or use several of the other available step - function - lookalikes, if you for example wish to smoothen the transition to 0 value).
  4. Sep 6, 2008 #3
    PerennialII ,

    Thanks for the reply. yup. I got the waveform as per the syntax that you have given. Right now I need to generate the temperature profile which I am facing some problem.

    Its not what I am expecting.
  5. Sep 7, 2008 #4


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    Yeah, these often take surprising chunks of time to get them working. Let me know if can try to come up with further pointers.
  6. Sep 8, 2008 #5
    If you like I can help you out with a simulation in Ansys. Let me know if you want my help.
  7. Feb 27, 2009 #6
    hi, im dont no nothing about COMSOL, apart from the using a user guid to make a model and plot a graph.. what i wish to achieve is a wire ( rectangle ) which gives heat at one end and over time the heat eventually transfers over to the other.

    Thanks kenn
  8. Feb 28, 2009 #7
    i think you cn try with the heat transfer using the conduction model to do this....try using tat and contact if u have any doubt
  9. Mar 2, 2009 #8
    as a complete novis to this software, could you explain to me in a step by step process how to achive a model of heat flow from one end of a wire to another? i would reli appreciate this, as well as a stress flow model aswell (where one end increases in tensile stress and the other end increases in compressive stress), many thanks
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