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How to get a solution for EDL

Posted 31 mar 2012, 04:16 GMT-4 Fluid & Heat, Computational Fluid Dynamics (CFD), Chemical Reaction Engineering, Studies & Solvers Version 4.2a 9 Replies

Hyomin Lee
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Hi.

I'm trying to solve the electric double layer structure using Nersnt-Planck eqn and Poisson eqn rather than Poisson-Boltzmann eqn.

My domain is pallel plate of which height is nanometric, typically ~10nm.

However, my model failed to converge.

Sometimes, converge is succed. But that result is not coincided with analytical solution.

What is the problem?

Is there anyone solved this problem?
9 Replies Last Post 13 mag 2013, 17:06 GMT-4
R. F. Hamou
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Posted: 1 decade ago 2 apr 2012, 06:16 GMT-4
Hi Lee,

Which values for the potential and electrolyte concentration are you considering?
Normally it should be simple and with the same manner as you have modeled the PB equation! The same definition for the charge density ( for Poisson equation)
You can upload your model and I will try to take a look!

Cheers
Hi Lee, Which values for the potential and electrolyte concentration are you considering? Normally it should be simple and with the same manner as you have modeled the PB equation! The same definition for the charge density ( for Poisson equation) You can upload your model and I will try to take a look! Cheers
R. F. Hamou
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Posted: 1 decade ago 2 apr 2012, 06:57 GMT-4
To make it simple for you and more instructive:
I have just found a simple old model that I have in my archives!

You can take a look and compare with your model and settings! Note that I am not assuming any electrochemical reactions at the electrode. It's similar to the PB equation.

(It's 4.2a model)


Good luck
To make it simple for you and more instructive: I have just found a simple old model that I have in my archives! You can take a look and compare with your model and settings! Note that I am not assuming any electrochemical reactions at the electrode. It's similar to the PB equation. (It's 4.2a model) Good luck

Attachments:

Hyomin Lee
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Posted: 1 decade ago 3 apr 2012, 04:31 GMT-4
Hi Hamou,

Thank you for your reply. I am really waitting for someone's help.

But I can not open your file, because my comsol version 4.2 rather than 4.2a.

My comsol license has been expired already, so i can not update later version.

Would you upload the file for lower version? e.g. 4.2 or 4.0 ok.

Thank you for your reply, one more time.
Hi Hamou, Thank you for your reply. I am really waitting for someone's help. But I can not open your file, because my comsol version 4.2 rather than 4.2a. My comsol license has been expired already, so i can not update later version. Would you upload the file for lower version? e.g. 4.2 or 4.0 ok. Thank you for your reply, one more time.
R. F. Hamou
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Posted: 1 decade ago 3 apr 2012, 09:18 GMT-4
Hi,
I am not using 4.0 or 4.2 any more ! But you are lucky, I am still keeping Comsol 3.5a lol

Actually this was an old 3.5a model that I am still keeping and I had to open it with 4.2a to re-edit it!
I uploaded the model under 3.5a, which can be opened by your 4.2 version.

Good luck!
Hi, I am not using 4.0 or 4.2 any more ! But you are lucky, I am still keeping Comsol 3.5a lol Actually this was an old 3.5a model that I am still keeping and I had to open it with 4.2a to re-edit it! I uploaded the model under 3.5a, which can be opened by your 4.2 version. Good luck!

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Hyomin Lee
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Posted: 1 decade ago 4 apr 2012, 04:10 GMT-4
Thank you Hamou.

I tried to solve the EDL structure between parallel plate,

and I was stuck using NP eqn and Poisson eqn.

I think that there's some bug in 'Transport of diluted species'' module.

When I rewrite NP eqn using PDE coefficient module, it works.

I get a proper solution for EDL structure between parallel plate through that approach.

Because of that problem, I have been confused for some weeks.

Although I sent e-mail to Comsol support mail, they said 'I have no effective license, so they have no responsibility to answer my question.'

Anyway, Thank you Hamou.

and to someones similiar to me, I suggest the way

Rewirte NP eqn using PDE module, then it works.

Thank you Hamou. I tried to solve the EDL structure between parallel plate, and I was stuck using NP eqn and Poisson eqn. I think that there's some bug in 'Transport of diluted species'' module. When I rewrite NP eqn using PDE coefficient module, it works. I get a proper solution for EDL structure between parallel plate through that approach. Because of that problem, I have been confused for some weeks. Although I sent e-mail to Comsol support mail, they said 'I have no effective license, so they have no responsibility to answer my question.' Anyway, Thank you Hamou. and to someones similiar to me, I suggest the way Rewirte NP eqn using PDE module, then it works.
Hyomin Lee
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Posted: 1 decade ago 4 apr 2012, 04:11 GMT-4
Thank you Hamou.

I tried to solve the EDL structure between parallel plate,

and I was stuck using NP eqn and Poisson eqn.

I think that there's some bug in 'Transport of diluted species'' module.

When I rewrite NP eqn using PDE coefficient module, it works.

I get a proper solution for EDL structure between parallel plate through that approach.

Because of that problem, I have been confused for some weeks.

Although I sent e-mail to Comsol support mail, they said 'I have no effective license, so they have no responsibility to answer my question.'

Anyway, Thank you Hamou.

and to someones similiar to me, I suggest the way

Rewirte NP eqn using PDE module, then it works.

Thank you Hamou. I tried to solve the EDL structure between parallel plate, and I was stuck using NP eqn and Poisson eqn. I think that there's some bug in 'Transport of diluted species'' module. When I rewrite NP eqn using PDE coefficient module, it works. I get a proper solution for EDL structure between parallel plate through that approach. Because of that problem, I have been confused for some weeks. Although I sent e-mail to Comsol support mail, they said 'I have no effective license, so they have no responsibility to answer my question.' Anyway, Thank you Hamou. and to someones similiar to me, I suggest the way Rewirte NP eqn using PDE module, then it works.
R. F. Hamou
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Posted: 1 decade ago 4 apr 2012, 05:57 GMT-4
To my knowledge, there is no bug in the NP equation! You are the first one to say that! and using the PDE formulation is the same story..no difference !!
Probably it's your model, which is bugging, not the NP equation in COMSOL.

Moreover, you didn't clarify and specify your real problem to the forum community here! Nobody would guess which kind of BUG you are talking about! May be we can investigate it..!?

Anyway, good luck ;) !

Ciao
To my knowledge, there is no bug in the NP equation! You are the first one to say that! and using the PDE formulation is the same story..no difference !! Probably it's your model, which is bugging, not the NP equation in COMSOL. Moreover, you didn't clarify and specify your real problem to the forum community here! Nobody would guess which kind of BUG you are talking about! May be we can investigate it..!? Anyway, good luck ;) ! Ciao
Hyomin Lee
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Posted: 1 decade ago 5 apr 2012, 01:28 GMT-4
Sorry to clarify my opinion.

As you told me, there are no bugs maybe.

But I can not find wrong point in my comsol model.

It is so strange for me.

Around me, there's no person who I ask the problem relating my model.

Anyway, Sorry to clarification and thank you, Hamou.

Your reply is a help to me.
Sorry to clarify my opinion. As you told me, there are no bugs maybe. But I can not find wrong point in my comsol model. It is so strange for me. Around me, there's no person who I ask the problem relating my model. Anyway, Sorry to clarification and thank you, Hamou. Your reply is a help to me.
Aoun Nejiba
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Posted: 1 decade ago 13 mag 2013, 17:06 GMT-4
Hi Hamou,
Your model is very difficult. do you give an another model more easily.
please help? I really appreciate your time!
Nejiba
Hi Hamou, Your model is very difficult. do you give an another model more easily. please help? I really appreciate your time! Nejiba

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