# analyzing the temperature of fliud (air) flow inside an underground duct.

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March 30, 2014, 14:46
analyzing the temperature of fliud (air) flow inside an underground duct.
#1
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Arshdeep Singh Chahal
Join Date: Mar 2014
Location: Dhariwal, Distt Gurdaspur, Punjab, India
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hello everybody, this is arshbunny. i am doing my project on air conditioning of a room using underground duct. i want to analyze the flow of air inside the underground duct. all know that the underground duct is at lower temperature than the atmospheric one in summers. the air enters the duct at 40 C, the temperature of the duct surface is 25 C, as the air will pass through the duct, due to convection heat transfer, it will get cooled up and provide the effect of air conditioning.
i have watched all cfx tutorials, conjugate heat transfer tutorials and almost near to the completion of the analysis. but i am unable to do two things:-

1.) i have analyzed the streamlines(velocity) and other contours, but i am unable to analyze the temeperature changes in the air streamlines as it travels inside the duct. this may be due to the fact that i havent inserted any expression, as i dont know how to insert an expression in cfx-pre.
Attached Images
 fluid domain.JPG (82.0 KB, 24 views) solid domain.JPG (79.3 KB, 22 views) streamline of velocity (but i need streamline specifying temperature changes).jpg (94.0 KB, 19 views)

 March 30, 2014, 18:07 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,817 Rep Power: 144 No need for any expressions. You will not see a temperature change by looking at streamlines. Have you tried looking at the temperature?

 March 31, 2014, 08:41 #3 New Member   Arshdeep Singh Chahal Join Date: Mar 2014 Location: Dhariwal, Distt Gurdaspur, Punjab, India Posts: 6 Rep Power: 12 yes i tried everything to see temperature change in the fluid...but it doesnt show

 March 31, 2014, 17:48 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,817 Rep Power: 144 Have you done the tutorial examples? This is basic post processing and is demonstrated in several tutorial examples.

March 31, 2014, 23:42
#5
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Quote:
 Originally Posted by arshbunny yes i tried everything to see temperature change in the fluid...but it doesnt show
What exactly you did? In CFD-Post you may place a plane and color it by temperature. If you can't see temperature changes then they may be small.

April 1, 2014, 04:20
need help
#6
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Deldan Namgial
Join Date: Mar 2014
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Quote:
 Originally Posted by arshbunny hello everybody, this is arshbunny. i am doing my project on air conditioning of a room using underground duct. i want to analyze the flow of air inside the underground duct. all know that the underground duct is at lower temperature than the atmospheric one in summers. the air enters the duct at 40 C, the temperature of the duct surface is 25 C, as the air will pass through the duct, due to convection heat transfer, it will get cooled up and provide the effect of air conditioning. i have watched all cfx tutorials, conjugate heat transfer tutorials and almost near to the completion of the analysis. but i am unable to do two things:- 1.) i have analyzed the streamlines(velocity) and other contours, but i am unable to analyze the temeperature changes in the air streamlines as it travels inside the duct. this may be due to the fact that i havent inserted any expression, as i dont know how to insert an expression in cfx-pre.
Mr arshdeep i need help as i m also doing similar work but in my case i m doing for agricultural greenhouse and i m not mechanical eng side...but i have to use gambit and fluent for my work,,,so can u plz tell is it possible to analyse such work in 3 d ? can u please share u e mail Id so that i can seek your help in details....

April 1, 2014, 13:54
#7
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Arshdeep Singh Chahal
Join Date: Mar 2014
Location: Dhariwal, Distt Gurdaspur, Punjab, India
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Quote:
 Originally Posted by Antanas What exactly you did? In CFD-Post you may place a plane and color it by temperature. If you can't see temperature changes then they may be small.
yes, i saw temperature variations at the "outlet" boundary of the "fluid" domain, but it shows weird values. at inlet, the air temp is 40 C and i expect it to reach 25 C at the outlet, but it shows the variation in -10 to -50 C. i think i am wrong in applying boundary conditions on the "solid" domain

April 1, 2014, 14:39
#8
New Member

Arshdeep Singh Chahal
Join Date: Mar 2014
Location: Dhariwal, Distt Gurdaspur, Punjab, India
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Quote:
 Originally Posted by deldan Mr arshdeep i need help as i m also doing similar work but in my case i m doing for agricultural greenhouse and i m not mechanical eng side...but i have to use gambit and fluent for my work,,,so can u plz tell is it possible to analyse such work in 3 d ? can u please share u e mail Id so that i can seek your help in details....
i didnt get you...please describe me in detail

 April 1, 2014, 18:38 #9 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,817 Rep Power: 144 arshbunny: Please post the CCL of what you are modelling, and the output file too if possible. Deldan: Please start a new thread for a new question. Do not hijack existing threads.

 April 3, 2014, 08:52 #10 New Member   Deldan Namgial Join Date: Mar 2014 Posts: 5 Rep Power: 12 ok so sorry for hijacking present thread

 Tags ansys 14 cfx, cfx & air content, cfx pre, expression