Saline solutions in FLUENT

MayTheFlowBeWithYou · June 19, 2017, 10:07

Dear CFD-Online community,

I am trying to simulate a reverse-osmosis/osmosis system, it basically consists of two "pipes" next to each other with a membrane in between. In one pipe flow pure water and in the other flows salt water. The simulation is in 2D

In fluent, the membrane is just a wall and I want to use a UDF to transport the salt ions over the wall like a membrane.

The big issue here is to model the dissolved salt. I am currently trying to use a User Defined Scalar (UDS) to model the salt concentration in mol/m3. However I have not Idea how to implement this. I set a flux of the UDS on the inlet and it just follows mass transport equations, but I have no idea what to do with the outlet. I can only set either a constant value or a flux there, which is incorrect and thus yields incorrect results.

Doe anyone have a better idea on how to tackle this problem?

I'd be happy to elaborate on anything, if it is not clear enough, please tell me.

lapis12 · January 17, 2019, 08:03

Well reverse osmosis system is just the mess you should move to Faucet filtration system

What do you think about this
But soon going to give it a try too. I have not used any Best RO water system before just heard this remarks from my community

MayTheFlowBeWithYou · January 18, 2019, 04:26

Wouldn't work. My goal was not to produce clean drinking water.

June 19, 2017, 10:07	Saline solutions in FLUENT	#1
MayTheFlowBeWithYou Member I have to remain anonymous, I'm sorry. Join Date: Jun 2017 Location: The Netherlands, Delft University of Technology Posts: 48 Rep Power: 9	Dear CFD-Online community, I am trying to simulate a reverse-osmosis/osmosis system, it basically consists of two "pipes" next to each other with a membrane in between. In one pipe flow pure water and in the other flows salt water. The simulation is in 2D In fluent, the membrane is just a wall and I want to use a UDF to transport the salt ions over the wall like a membrane. The big issue here is to model the dissolved salt. I am currently trying to use a User Defined Scalar (UDS) to model the salt concentration in mol/m3. However I have not Idea how to implement this. I set a flux of the UDS on the inlet and it just follows mass transport equations, but I have no idea what to do with the outlet. I can only set either a constant value or a flux there, which is incorrect and thus yields incorrect results. Doe anyone have a better idea on how to tackle this problem? I'd be happy to elaborate on anything, if it is not clear enough, please tell me.

January 17, 2019, 08:03		#2
lapis12 New Member Lapis Bolt Join Date: Dec 2018 Posts: 1 Rep Power: 0	Well reverse osmosis system is just the mess you should move to Faucet filtration system What do you think about this But soon going to give it a try too. I have not used any Best RO water system before just heard this remarks from my community Last edited by lapis12; January 22, 2019 at 11:32.

January 18, 2019, 04:26		#3
MayTheFlowBeWithYou Member I have to remain anonymous, I'm sorry. Join Date: Jun 2017 Location: The Netherlands, Delft University of Technology Posts: 48 Rep Power: 9	Wouldn't work. My goal was not to produce clean drinking water. __________________

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