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-   -   PEM modeling UDS diffusivity in mixture (http://www.cfd-online.com/Forums/fluent/48926-pem-modeling-uds-diffusivity-mixture.html)

gemini August 1, 2008 04:54

PEM modeling UDS diffusivity in mixture
 
Hi,

I am modeling PEM fuel cell using UDFs. For the definition UDS diffusivity (e.g. electric potential ) I wrote a UDF that assign different diffusivity values for different zones of fuel cell. In meterials panel for solid materials I hook this UDF succesfully and it works. But it does not work correctly for porous fluid zones such as gdl catalyst layer and flow channels. Is there any way to assign very small diffusivity for specified porous zones. I tried mixture UDS diffusivity definition in material panel however when I start iteration solution diverges.

Also, is FLUENT use solid material UDS diffusivity value or fluid mixture UDS diffusivity for solving a UDS in porous zones?

have a nice day...


pour August 13, 2008 13:28

Re: PEM modeling UDS diffusivity in mixture
 
hi I write udf to fuel cell simulation,I have some problem with udf for example i dont know how i add nonlinear source terms (transfer current) in electrical equation or i dont know how i simulate membrane ?. could i collaborate with you ? my mail : pourak_mechfluid@yahoo.com best regards Pourak

gemini August 15, 2008 06:28

Re: PEM modeling UDS diffusivity in mixture
 
Hi Pourak,

I have a lot of problem with modeling with UDF. Like you, I could not have a solution for highly non-linear terms up to now. I tried Picard's method to linearize Transfer current source term of solid and membrane phase potential equation but i diverges at the first iteration. So I have nothing in my PEM modeling. If I found a way to successfully incorporate the reaction source term for phase potential I will explain its details in here. However, if you have any idea about that we can make discussion in order to solve the problem.

Regards

Gemini


pour August 20, 2008 11:49

Re: PEM modeling UDS diffusivity in mixture
 
hi gemini thanks for reply,we can make discussion together. my mail is : pourak_mechfluid@yahoo.com do you send your mail to me ? do you use single phase model ? best regards pourak


Gemini August 25, 2008 07:44

Re: PEM modeling UDS diffusivity in mixture
 
Hi Pourak,

I am currently use single phase model. Although I linearized the Butler-Volmer equation I got nan errror for protonic potential equation, I could not solve this issue. Is there any progress on your side.

Best regards

Gemini

neeharmokal November 24, 2009 03:48

if i am not mistaken then the DEFINE_SOURCE function uses picard method to linearize.

elemad1987 August 7, 2012 07:37

happen History repeat it self
 
guess what happenHistory repeat it self.

I have the same problem as you

I am using the Fluent 14 and I want to simulate a PEM fuel cell.
The only tutorial of PEM fuel cell of Fluent is from 6.3 version.
I use it to Fluent 14 and I follow the steps but the results does not the same, also some data and parameters are different.

Anybody know if the tutorial of 6.3 Fluent is working to Fluent 14 too?
I think now you had finish your thesis peacefully.
Can you help me to overcome my problems.
or send me your cas files.

Thank you
Emad G.
elemad1987@gmail.com


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