# Thermal boundaray conditions

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 July 27, 2019, 17:04 Thermal boundaray conditions #1 New Member   Edwin P Join Date: Jun 2018 Posts: 13 Rep Power: 7 Hello, I have a long duct opened at atmospheric pressure. I want to model a small section near to the end of the duct which generates heat. I have transient measurements of temperature at the beginning and at the end of the that section. At time t=0, all the system is at ambient temperature. Should I use both the inlet and oultlet temperature measurements of my sections as a boundary conditions in Ansys Fluent? Help me please, Regards Светлана likes this. Last edited by intied; July 27, 2019 at 17:05. Reason: typo error

 July 29, 2019, 01:48 #2 Senior Member   Alexander Join Date: Apr 2013 Posts: 2,347 Rep Power: 33 from my point of view it depends on the goal of your simulation. Make a decision -> what you want to simulate, then put boundary conditions best regards Светлана likes this.

 July 29, 2019, 02:52 #3 Senior Member   Svetlana Tkachenko Join Date: Oct 2013 Location: Australia, Sydney Posts: 407 Rep Power: 14 Why is the temperature transient? Is this an externally imposed boundary condition in the experiment?

July 29, 2019, 11:53
#4
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Edwin P
Join Date: Jun 2018
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Quote:
 Originally Posted by Светлана Why is the temperature transient? Is this an externally imposed boundary condition in the experiment?

The temperature increase inside the duct is due to a solid with internal heat generation. I added a source term and I want to model its transient temperature profile

 July 29, 2019, 13:01 #5 Senior Member   Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,576 Rep Power: 64 You can't impose an outlet temperature, not that you would need to, anyway. You would just use pressure outlet or outflow BC or something. Just make sure you have the right inlet conditions and whatever else you need for your simulation. I can't follow what you want to do with heat generation and an inlet temperature.

July 29, 2019, 16:18
#6
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Edwin P
Join Date: Jun 2018
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Quote:
 Originally Posted by LuckyTran You can't impose an outlet temperature, not that you would need to, anyway. You would just use pressure outlet or outflow BC or something. Just make sure you have the right inlet conditions and whatever else you need for your simulation. I can't follow what you want to do with heat generation and an inlet temperature.

Thank you.

In fact, I am using pressure inlet and pressure outlet as boundary conditions. But, I am not sure if I have to use the transient temperature profile in the "Thermal" tab of those boundary conditions.

By other hand, I have a small solid which generates heat. I want to model its transient temperature.

July 29, 2019, 19:25
#7
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Edwin P
Join Date: Jun 2018
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Quote:
 Originally Posted by Светлана Why is the temperature transient? Is this an externally imposed boundary condition in the experiment?

I have a small solid which generates heat due to joule effect. Therefore, near to that soild, the ambient temperature changes.

Thank you

 Tags boundary conditions, temperature