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Heat Source Value as a Function of Coordinate

Posted Mar 21, 2011, 8:52 a.m. EDT Heat Transfer & Phase Change Version 3.5a 3 Replies

OD Tuna
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Hello,

I am trying to implement an introductory 2D model of a glass furnace in COMSOL 3.5. My first model was simple: geometry of a common glass furnace with a horizontal boundary heat source at the top having constant W/m^2, and inlets/outlets having boundary conditions as constant velocities.

Now, I am trying to add a more complex boundary heat source, where the temperature of the surface is a function of the x-coordinate. Naturally, the center of the heat source will be where the peak temperature happens, so I am first trying to implement
(1/(sqrt(2*pi)))*exp(-((x+1.5)^2)/2)

namely, a Gaussian distribution having its mean at x=-1.5.

Is such an implementation possible? If so, how can I write the expression above as a function of "the x coordinate" in COMSOL? How can I appoint this function to the boundary heat source?

Best regards,
ODT
3 Replies Last Post Mar 22, 2011, 10:13 a.m. EDT
Xiaogai Li
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Posted: 1 decade ago Mar 21, 2011, 9:36 a.m. EDT
Hi,

The expression should already work.
Comsol can recognize this "x" in the expression (1/(sqrt(2*pi)))*exp(-((x+1.5)^2)/2).
You can check the "geometry variables".
XLi
Hi, The expression should already work. Comsol can recognize this "x" in the expression (1/(sqrt(2*pi)))*exp(-((x+1.5)^2)/2). You can check the "geometry variables". XLi
OD Tuna
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Posted: 1 decade ago Mar 22, 2011, 6:03 a.m. EDT
Hello XLi, thanks for your quick reply.
When I change the q0 value (inward heat flux) for the boundry whose condition is heat flux with the expression above, I get "failed to find consistent initial values" and "last time step is not converged" errors. I used to tweak inlet/outlet values and solver parameters to get over this problem, but now it seems those tricks dont work anymore. Any ideas?

Thanks in advance,
ODT
Hello XLi, thanks for your quick reply. When I change the q0 value (inward heat flux) for the boundry whose condition is heat flux with the expression above, I get "failed to find consistent initial values" and "last time step is not converged" errors. I used to tweak inlet/outlet values and solver parameters to get over this problem, but now it seems those tricks dont work anymore. Any ideas? Thanks in advance, ODT
Xiaogai Li
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Posted: 1 decade ago Mar 22, 2011, 10:13 a.m. EDT
Maybe you can try
1. to run a steady state model see if it works.
2. change the values of the parameters, for example, use a smaller heat source, or smaller inward flux, larger out ward flux.
See where is the problem.
Maybe you can try 1. to run a steady state model see if it works. 2. change the values of the parameters, for example, use a smaller heat source, or smaller inward flux, larger out ward flux. See where is the problem.

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