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Modeling of diffusion

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Hello!
I would like to model the diffusion of dopants into a bulk material from a thin layer on its surface . As I understand, in my COMSOL version (4.4) I should use the module "Transport of Diluted Species". But during the diffusion the dopant layer should decrease. How could I build the model?

5 Replies Last Post Dec 20, 2016, 11:07 a.m. EST

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Posted: 10 years ago Jan 27, 2015, 3:56 a.m. EST
You have thin layer with some initial dopant concentration. Assign the "No flux" condition on the boundary which is facing the "outside world", and at boundary between the layer and bulk no condition is necessary as COMSOL assumes continuity across inner boundaries. Of course, if you have some specific condition on that boundary, use it. I could attach a model but I am using version 5.0. Yet, attached the report file which may help you.

br
Lasse
You have thin layer with some initial dopant concentration. Assign the "No flux" condition on the boundary which is facing the "outside world", and at boundary between the layer and bulk no condition is necessary as COMSOL assumes continuity across inner boundaries. Of course, if you have some specific condition on that boundary, use it. I could attach a model but I am using version 5.0. Yet, attached the report file which may help you. br Lasse

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Posted: 10 years ago Jan 27, 2015, 3:58 a.m. EST
And the attachments
And the attachments


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Posted: 10 years ago Jan 27, 2015, 12:09 p.m. EST
Well, but in such model the dopant layer won't decrease. It will be only a part of diffusion area. However, in the reality dopants diffuse in, and specially created conditions prevent outdiffusion.

If a have misunderstood your idea, please send me your model, it doesn't matter which version it has.
Well, but in such model the dopant layer won't decrease. It will be only a part of diffusion area. However, in the reality dopants diffuse in, and specially created conditions prevent outdiffusion. If a have misunderstood your idea, please send me your model, it doesn't matter which version it has.

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Posted: 10 years ago Jan 28, 2015, 2:29 a.m. EST
If you mean that the thickness of the dopant layer does not decrease you are right. In my model only the concentration of the dopant in the layer decreases. If you want the thickness to decrease, I do not know how to do it.
If you mean that the thickness of the dopant layer does not decrease you are right. In my model only the concentration of the dopant in the layer decreases. If you want the thickness to decrease, I do not know how to do it.

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Posted: 8 years ago Dec 20, 2016, 11:07 a.m. EST
Could you please send me the diffusion model I need to study the diffusion between a gas and a liquid either in 3d or in 2d
Could you please send me the diffusion model I need to study the diffusion between a gas and a liquid either in 3d or in 2d

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