pdetool concentration profile simulation
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I want to use pdetool to simulate the hydrogen concentration profile based on the fick's second law in two dimensional system. the model is like this, there is two joined region A and B. diffusion coefficient in A is faster than that in B. hydrogen diffusion in this two region is 2 dimension(along x and y). they have the same boundary condition, for example the initial concentration is constant and same in A and B. how do we set the different diffusion coefficient in this two region? how should I do with the border between A and B region, since hydrogen will diffuse from A to B (y direction) since it is faster in A region. To me, it seems that after I set the boundary condition, I can not set different D in this two region.
采纳的回答
Alan Weiss
2016-3-21
1 个投票
You can set different D in the PDE app by selecting PDE > PDE Mode and then double-clicking each region to set its coefficients. I assume that you already set the problem type to Diffusion.
Alan Weiss
MATLAB mathematical toolbox documentation
更多回答（2 个）
Wen huang
2016-3-21
0 个投票
2 个评论
Alan Weiss
2016-3-22
I cannot reproduce your problem exactly, though on occasion I, too, have seen that the boundary conditions or coefficients sometimes seem to change in an unpredictable fashion. This can occur when you change the problem type in the middle of setting up your problem.
I suggest that you draw the geometry first, immediately set the problem type (diffusion), then set the boundary conditions, and then the diffusion coefficients. I believe that you will not have any problems if you set things in this order.
Good luck,
Alan Weiss
MATLAB mathematical toolbox documentation
Wen huang
2016-3-25
Thanks very much, but I still can not figure it out after I play with the steps you told me there, I must have made some mistakes. but I do not know where it is. I just list what my step is,and hopefully you can see where my mistake is.
Firstly, I draw 2 rectangle region, one of the sides for each region overlaps with each other, as shown in the first image. I also already set type of problem(diffusion). </matlabcentral/answers/uploaded_files/48468/1.png>
Secondly, I set the boundary condition(I choose the boundary mode, then specify the details), you can see this in the second image
Thirdly, I define the diffusion coefficients, I found that I can not choose the regions separately, so I directly go to PDF menu and can set D(i only can set one D), but I can not set different diffusion coefficients for this two regions separately. I am curious how you realize this. As I said before, if I define different D after I draw the first image immediately, the D will become same after I define boundary condition and mesh.
Thanks very much, and I hope you can see where my problem is this time, and give me a very detailed step to solve my problem. I never use pdetool before.
Wen huang
2016-3-25
0 个投票
this is the first image.
2 个评论
Wen huang
2016-4-4
Alan Weiss
2016-4-4
As I said, I cannot reproduce your problem. When I follow the exact steps I told you, then I can set the coefficients differently in the two domains. I am sorry not to be able to help you more.
You could try Technical Support and see if they can help.
Alan Weiss
MATLAB mathematical toolbox documentation
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