[Shivam Gupta]

Hello, CFD folks!

For the past two weeks, I have been trying to simulate the dehumidification and simultaneous cooling of hot, humid air entering the domain in Ansys Fluent. The geometry of the same is shared below.

In brief, The hot humid air is entering the domain while the water vapour in the flow is being absorbed by the membrane, resulting in dehumidification. Also, several cooling pipes are placed parallel to the flow to cool the entering flow simultaneously.

I've figured out all the physics setup except for the membrane boundary condition. I want to specify different exiting mass flux for water vapour and air exiting from the membrane. I'm not able to find any pre-defined BC in fluent that could work for me. I have tried using "mass flow outlet" and even "mass flow inlet" to specify selective mass flux for different species but could not get any realistic results.

After reading some literature, I learned that we could specify a global sink source to the first layer of cells near membrane to achieve required BC. That process may include writing UDFs and calculating proper source term for continuity, momentum and energy equations. I have no idea on how to use UDFs and calculate the required source terms in fluent.

I have been stuck on this problem for a long time so, If anyone can help me with this in any way, please feel free to put your suggestions in the comments below.

P.S. - I have utilised the species transport equation to model air and water vapour in the hot, humid air.

If you didn't understand any part of the query, please feel free to contact me at kumar455shivam-at-gmail.com.[IMG][/IMG]