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-   -   Source Term UDF VS Porous Media Model (http://www.cfd-online.com/Forums/fluent-udf/96615-source-term-udf-vs-porous-media-model.html)

pchoopanya January 27, 2012 05:56

Source Term UDF VS Porous Media Model
 
Hello from Thailand,

I am new to UDF and computer programming.

I need to model a PEM fuel cell's flow channel and got stuck on this UDF thing.

I am familiarising myself to the coding starting from, I believe, the simplest of all - source term UDF.

I follow the first tutorial which is the flow in a porous media with a user-defined momentum source term. One question pops up in my head, I have done one tutorial regarding a flow in porous media but with no UDF. The tutorial showed me how to activate the porous model (based on Darcy's law?).

My question is, what is the point of coding the source term via UDF function if we already have this built-in porous media model? Is UDF more accurate?

My next step is to incorporate a simple chemical reaction (Hydrogen + Oxygen = Water + heat). Again, I have done the tutorial regarding chemical reaction but it is more like combustion reaction in the ICE engine (hydrocarbon + oxygen). I cannot find any tutorial to show me how to model the reaction in PEM fuel cell at all. Seems like the others have done this via the UDF source term in order to predict the hydrogen/oxygen consumption rates and water generation rate.

So, is it worth trying to find the way to model the H+O reaction without coding UDF source term? I am asking this because I am so scared of computer programming, but this seems to be unavoidable! Can anyone just assure me that the only way is via UDF? In fact, I am learning the basic C language/coding and I want to be sure that I am on the right track.

Again, can anyone emphasise the necessity of UDF for my PEM fuel cell modelling? I am waiting for the purchase of their PEM fuel cell Add-on Module. But while I am waiting I believe I would be able to build my own model with the use of UDFs and the standard FLUENT. Am I right?

Thank you very much for your comments, sorry for my poor English.




Pattarapong

harsh_999 August 28, 2013 06:12

Quote:

Originally Posted by pchoopanya (Post 341460)
Hello from Thailand,

I am new to UDF and computer programming.

I need to model a PEM fuel cell's flow channel and got stuck on this UDF thing.

I am familiarising myself to the coding starting from, I believe, the simplest of all - source term UDF.

I follow the first tutorial which is the flow in a porous media with a user-defined momentum source term. One question pops up in my head, I have done one tutorial regarding a flow in porous media but with no UDF. The tutorial showed me how to activate the porous model (based on Darcy's law?).

My question is, what is the point of coding the source term via UDF function if we already have this built-in porous media model? Is UDF more accurate?

My next step is to incorporate a simple chemical reaction (Hydrogen + Oxygen = Water + heat). Again, I have done the tutorial regarding chemical reaction but it is more like combustion reaction in the ICE engine (hydrocarbon + oxygen). I cannot find any tutorial to show me how to model the reaction in PEM fuel cell at all. Seems like the others have done this via the UDF source term in order to predict the hydrogen/oxygen consumption rates and water generation rate.

So, is it worth trying to find the way to model the H+O reaction without coding UDF source term? I am asking this because I am so scared of computer programming, but this seems to be unavoidable! Can anyone just assure me that the only way is via UDF? In fact, I am learning the basic C language/coding and I want to be sure that I am on the right track.

Again, can anyone emphasise the necessity of UDF for my PEM fuel cell modelling? I am waiting for the purchase of their PEM fuel cell Add-on Module. But while I am waiting I believe I would be able to build my own model with the use of UDFs and the standard FLUENT. Am I right?

Thank you very much for your comments, sorry for my poor English.




Pattarapong



Hi Pattarapong,
if your transport equation contains source term then you have to write udf to account it while solving that,as FLUENT doesn't consider it
U need not 2 learn C language, there are predefined macros and u have to enter d logic in given syntax
Which tutorial u r talking about?
Let me have a look at it as I want to work on porous media
Please send it to this mail id: hhs999@gmail.com
Thanks n all d best


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