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Set these boundary conditions in COMSOL 3.4?

  1. May 25, 2008 #1
    Hello friends,
    Thanks in advance for your answers,

    I am using genreal form of PDE to solve system of PDEs. I am dealing with cyllindrical co-ordinates under axisymmetric case. I am not able to understand how to implement boundary conditions such as,

    DEL. Gamma=F is system of PDEs
    where Gamma is function of (u, v, ur, uz,vr,vz..)

    I would like to set u=0 and vr=0 on one of boundary, vr stands for derivative of v w.r.t. r.

    can any one tell me how to set these boundary conditions in COMSOL 3.4?

    Thanks again.
  2. jcsd
  3. Oct 24, 2008 #2


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    Science Advisor
    Gold Member

    Re: Comsol

    You can give Dirichlet, Neumann or mixed BCs directly from physics --> boundary (depending on your application mode), or then you can go about it via physics --> equation systems and work with the boundary terms for the PDE you're working with or define something specific for a boundary in question (if you need something more general). If you've something beyond this there are further means, Comsol is fairly general this way.
  4. Jan 5, 2010 #3
    PCFs and COMSOL

    Hello everyone, I am trying to understand COMSOL 3.5 and I am interested in Photonic crystal fibres and tapered optical fibres. First of all, could you please tell me what is the background of the layout? When you create a design/object, the rest area is air or I need to define another object as the environment?
    Now, could you please tell me where I can find instructions of how creating a PCF structure in COMSOL? Furthermore, do you know any good notes/books for COMSOL for photonic applications??
    Thank you in advance

  5. Jan 6, 2010 #4
    Re: Comsol


    Did you check out the models and documentation that comsol provides? They have some examples that once the work through may be helpful. I think it has an optical fiber example in there. That's pretty much how I have taught myself Comsol. I don't know of any good books that are out and I have looked around. Maybe someone else knows of one?

  6. Jan 6, 2010 #5
    Re: Comsol

    Dear Jacob,
    Thank you for your reply. Of course I have checked the examples and the one with the optical fibre; however an optical fibre is a very simple structure and quite different from a photonic crystal fibre and a tapered fibre (of diameter 1um without cladding). Furthermore, due to fact that these models are ready, I dont really know every parameter used in the model because its default and unfortunately the documentation does not explain in details. Thank you for your reply and your time, though. I hope that someone else is also faced with similar problems and will give an answer.

    Best Regards,
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