COMSOL+Heat Transfer

  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?

    Thanks.
     
  2. jcsd
  3. PerennialII

    PerennialII 1,102
    Science Advisor
    Gold Member

    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:

    (10^7)*exp((-10^3)*x^2)*(t<=2)

    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. 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. PerennialII

    PerennialII 1,102
    Science Advisor
    Gold Member

    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. If you like I can help you out with a simulation in Ansys. Let me know if you want my help.
     
  7. 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. 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. 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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