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-   -   how to give a temperature condition for a domain? (http://www.cfd-online.com/Forums/fluent/103199-how-give-temperature-condition-domain.html)

 arun_thakur June 13, 2012 08:21

how to give a temperature condition for a domain?

hi,
i am using fluent for a scenario in which air is coming inside the room at a certain temperature and the air inside i want to keep at certain temperature. Purpose is to see the mixing behaviour of air.
but problem is how to give the temperature to the air inside the room.

it may be very silly question. But to be honest i need help on this.

rgds.

 Kwiaci June 13, 2012 10:57

You need to create a separate volume for the air in the room, at the boundary of fluid use internal boundary, patch temperature inside the room and choose one of the multiphase models.

 vigneshkumar_t June 30, 2012 01:52

Which multi phase option will be better since same air will be for both the domain?

 arun_thakur July 2, 2012 08:22

making separate volume is not so easy task for every different encountering problems..and how we can use multiphase when we are taking about same air only difference is temperature...??

 robboflea July 2, 2012 11:57

Sorry but I'm missing something. You have a volume (say a room) with air at a certain temperature and a current of air (at a different temperature) coming from a inlet in the room walls. Am I right?
In this case you don't have constant temperature in the room. If you're mixing two air streams at a different temperature you'll never have constant temperature.

Rob

Quote:
 Originally Posted by arun_thakur (Post 369267) making separate volume is not so easy task for every different encountering problems..and how we can use multiphase when we are taking about same air only difference is temperature...??

 flotus1 July 3, 2012 03:02

What is the point of a multi-phase computation in this case?

Just set the initial temperature of the fluid inside your room to the desired temperature.

At the inlet, set the temperature of the fluid entering your room. now all you need is an outlet and a transient simulation and you are good to go.

Keeping the temperature in the room at a constant temperature all the time would be possible ("Cell Zone Conditions" -> "edit" -> check "fixed values" ->"fixed values" tab -> specify temperature; or via UDF). But if I am not missing something essential here, you would not see any mixing of temperatures since the temperature will be constant throughout the domain.

 arun_thakur July 5, 2012 05:21

Quote:
 Originally Posted by robboflea (Post 369324) Sorry but I'm missing something. You have a volume (say a room) with air at a certain temperature and a current of air (at a different temperature) coming from a inlet in the room walls. Am I right? In this case you don't have constant temperature in the room. If you're mixing two air streams at a different temperature you'll never have constant temperature. Rob
you are absloute right it could not be constant temperature.It needs a transient case but problem is have tried every thing but results are not coming in favour.

how u define the problem is absolutely right.I have to see the mixing of outside air with the insider air of room.But its not giving the exepcting results. Even in transient its showing all the room temperatrue equal to entering air temp at just start. which could not be possible. in actual walls are insulated too to keep the difference of 10 deg to outside.

either i have to run it pressure based or density based.

i have no clue where i'm making a mistake.

 flotus1 July 5, 2012 05:45

Would you like to show us the computational domain and the boundary conditions of your setup?

 arun_thakur July 31, 2012 03:30

sorry for replying so late. I found out the solution for my problem.

it should be run as a transient and initialization condition should not be the default temp calculated by fluent but here need to put as temerature of air entering inside the room.

 Hybrid March 4, 2016 23:57

Would you please share the complete solution what you have done, I have similar problem. Please refer to the link: http://www.cfd-online.com/Forums/flu...wo-fluids.html

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