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Enable this option: cl.ly/101N

Thanks for the reply Danial.
I have already enabled this option, but unable to find the underlying equation setting (in general/coefficient form) in structural physics.
Pls let me know, where to find these equation settings.

Thanks,
Rakesh

I got the equation settings.
It was hiding below the material model.

thanks,
Rakesh

Enable this option: cl.ly/101N

Hi,

The link above is missing at this time.
I have an electromagnetic simulation where I would like to change the wave equation in a domain (I'd like to add a source term) and have COMSOL work with that.

In the attached image you can see the Model Builder tree with the Wave Equation item selected. To the right there's the equation. I'd like to change it so instead of the equality to zero, it would be equal to something else.

I found the "Equation View" item (also shown in the image), however, I couldn't find a textbox with the wave equation. I started reading about "weak from" but I'm not sure it's what I'm looking for.

I'd appreciate some direction.

Thanks

Hi,

Enable equation view using the icon right to the the model builder tab.
Pls find the attached image for more details.

I hope this answer your question. If you still do not resolve the problem,
share your file.

Rakesh

Hi,

Thank you for the quick reply. I found what you were talking about, however, I do not understand where (or even IF) I can modify the equation.

I'll rephrase: in the attached image the equation is marked in green, to the right. I would like to add an arbitrary source term to it, as depicted. To my understanding, I should click "Equation View" (marked in cyan to the left) and modify something there, but, I do not know what. Nothing seems similar to an equation, nor to an intuitive "curl(curl(E)) - ... = 0" definition.
I've been looking in the COMSOL documentation, but it's so vast I can't sort through it..

Any help is appreciated.

Hi,

I don't have emf physics license.
Please generate the complete report of the comsol model and share.

-Rakesh

Hi,

Attached is the complete report. The equation I'm looking to modify is in the image in my recent post, as explained there. The material dispersion function "nektp()" is currently irrelevant, so pay no attention to it.

Eventually, the model should simulate second-harmonic generation in a nonlinear crystal. The basic idea is to have two, coupled wave equations in the given domain, one for the fundamental (frequency omega) and one for the second harmonic (2*omega). Therefore, I would create two "Electromagnetic Waves" physics, and add source terms (polarization source) to each of the wave equations, coupling them to one another.

As stated previously, I am unsure if it is possible to modify the wave equation at all. I read about "weak form" but still can't find something familiar in the whole list of expressions (see report). I could rewrite the whole EMW model with the Mathematics/Helmholtz model, but that seems silly.

Thank you for your assistance.

Hi,

Thank you for the quick reply. I found what you were talking about, however, I do not understand where (or even IF) I can modify the equation.

I'll rephrase: in the attached image the equation is marked in green, to the right. I would like to add an arbitrary source term to it, as depicted. To my understanding, I should click "Equation View" (marked in cyan to the left) and modify something there, but, I do not know what. Nothing seems similar to an equation, nor to an intuitive "curl(curl(E)) - ... = 0" definition.
I've been looking in the COMSOL documentation, but it's so vast I can't sort through it..

Any help is appreciated.

The vector equation must be divided into components to be able to implement in COMSOL. So what you see in the equation system contains partial derivatives rather than vectorial operators. It is not difficult to identify the components of Maxwell's equations correspondingly.

Cheers!

Why can I find it in COMSOL 4.2a, can you help me?

I am facing the same problem.
How can I edit the the equation as it was in v3.5?
it was available in v3.5 through (physics>equation system>...)

Click on the eye symbol just below the model builder tab.

Thank you!

Hi Danial

You can define a global equation and frame the equation by yourself and using this equation ,you can solve the model. The global equation can be defined under Physics tab-Global equations

Hope this helps!

Cheers