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jpinho June 9, 2009 11:57

Porous medium knudsen flow / Adsorption
Hello everyone,

I am trying to model the adsorption phenomena using a knudsen flow of gas in a porous medium of coal.

The idea is to relate the adsorption rate of the gas to the porous medium percentage of the coal, and study how the orientation and quality of coal impacts on the quantity of gas adsorbed.

Is it possible using Fluent? Any suggestion or articles focusing this kind of problems?


_Greg_ July 8, 2009 09:29


Yes it is possible to do it with UDF in FLUENT and actually, i would like to know if it is possible to do it with OpenFOAM as well.

jpinho July 8, 2009 11:47

hello greg,
thanks for your reply..
can you tell me more about that code in UDF? which kind of physics would you enable in fluent to study this case?


_Greg_ July 9, 2009 04:47

It depends on what you want to describe during adsorption : In my case, i modelize the 2D flow in the column scale and for the macropores concentration and the adsorbed quantities i developed an UDF. The mass and heat transfer due to adsorption is taken into account through source terms on species transport and energy equations. The macropores concentrations are UDS and adorbed quantities are calculated according to the isotherms ( langmuir, BET...etc )

hope this could help,

jpinho July 9, 2009 07:35

thanks greg,

my problem does not have chemical reaction as it is just the gas adsorption in the coal surface. when i enable transport and reaction fluent asks me always the chemical reaction properties and i rally have any idea how to fix it.

actually my graduation is mechanical engineering so im not so used to study this kind of physics.. is it possible that you send me a case file, even a very simple one, so i can understand a little more what you are describing?

it would be great and very useful..

_Greg_ July 9, 2009 08:45

I am sure you can easily understand that i cannot send you a case file for confidential reasons.

However, it''s not necessary to enable chemical reaction to modelize adsorption since you can develop for example, your own adsorption model with UDF as described in my previous post.

I am sorry i cannot help you more on this topic but UDF solutions are a way to achieve your goal as long as your are a bit familar with UDF coding.

Moreover, you don't need to be an expert in adsorption to implement isotherms models that you can find in the litterature.

good luck,

Deependra July 7, 2015 06:14

UDS fro wall adsorbtion
Hi Greg,

Can you please tell me that how to set up UDS for simulating wall adsorption. I want to use Langmuir model for this which is ::

dm/dt =Ka*C-Kd*m

where m = adsorbed mass per unit area on wall surface for considered species.
C = volumetric average of concentration for considered species
Ka,Kd = adsorbtion and desorbtion coefficient respectively which are known.

what I know that I have define a source term for this and also need to use UDS.I know about things, just confuse that how all these things together work.

Please Please help me , I have been working on this problem since two months as part of my master thesis, I know problem is not that complicated ,its just about getting all things together right.

I have already posted these queries on this forum three time but no one replied and tried to help me :mad:, so trying again, please reply this time.

I would be happy to mention your name for expressing thanks in my master thesis .

Please reply..:)

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