heat transfer distribution

malay · October 29, 2012, 07:06

I have simulated problem , the base of channel is a heat transfer source ( constant ) , when i plot the total surface heat transfer flux at this section ( the base of the channel ) , its appear as a constant line exept at the end and beginning of the channel ?! i need sombody help me why this happen ??

malay · October 29, 2012, 23:08

can somebody get me some help ??

A7A · October 30, 2012, 00:04

Hi,

What is the type of BC you gave to the base of the channel, is it heat flux or temperature?

sofie1 · October 30, 2012, 00:38

Hi
Is your geometry 2D or 3D

malay · October 30, 2012, 00:40

Quote:

Originally Posted by sofie1

Hi
Is your geometry 2D or 3D

Thanks for reply ......

my geometry is 3D

malay · October 30, 2012, 00:41

Quote:

Originally Posted by A7A

Hi,

What is the type of BC you gave to the base of the channel, is it heat flux or temperature?

thanks for reply .......

heat flux

A7A · October 30, 2012, 09:30

As the BC is heat flux, fluent will give you this result(constant heat flux), and if you want to check how the heat flux is changing along the channel base you have to use temperature as BC for the channel base.

malay · October 30, 2012, 09:32

Quote:

Originally Posted by A7A

As the BC is heat flux, fluent will give you this result(constant heat flux), and if you want to check how the heat flux is changing along the channel base you have to use temperature as BC for the channel base.

but why there is jump in the end and the bedninig ??

A7A · October 30, 2012, 09:42

I dont know why fluent give this jump, but have you checked the temperature variation along the channel base, and the heat transfer coefficient. If there isnt any thing wrong so it maybe something related to the nature of the mesh you are using.

malay · October 30, 2012, 09:46

Quote:

Originally Posted by A7A

I dont know why fluent give this jump, but have you checked the temperature variation along the channel base, and the heat transfer coefficient. If there isnt any thing wrong so it maybe something related to the nature of the mesh you are using.

the Tem distribution is ok but the Nu number dont go to standard ( 4.3 ) , Nu go to zero ??

A7A · October 30, 2012, 09:49

could you put a picture of temperature and Nu plots.

malay · October 30, 2012, 11:34

Quote:

Originally Posted by A7A

could you put a picture of temperature and Nu plots.

i attached the pictures

A7A · November 3, 2012, 03:52

The temperature of the channel base is decreasing, so Nu number must be increasing along the channel base, but Nu plot doesnt give you this result because of the jump of Nu number at the end of channel, so try to decrease the range of the Y-axis of the plot to see what is the real distribution of Nu number.

malay · November 5, 2012, 11:21

Quote:

Originally Posted by A7A

The temperature of the channel base is decreasing, so Nu number must be increasing along the channel base, but Nu plot doesnt give you this result because of the jump of Nu number at the end of channel, so try to decrease the range of the Y-axis of the plot to see what is the real distribution of Nu number.

thanks for reply ...
what about Nu no didnt go to 4.32

A7A · November 7, 2012, 11:19

Have you checked the reference values you are using like length and temperature.

malay · November 7, 2012, 11:21

Quote:

Originally Posted by A7A

Have you checked the reference values you are using like length and temperature.

yes i have checked it ...also i try to change it but still no way ..

carlt336 · March 7, 2013, 00:52

Malay, did you solve your problem with the heat transfer spikes at each end? I am having similar issues. Could it be a problem in the mesh?

malay · March 7, 2013, 02:06

Quote:

Originally Posted by carlt336

Malay, did you solve your problem with the heat transfer spikes at each end? I am having similar issues. Could it be a problem in the mesh?

not yet ... do you have any idea ?

carlt336 · March 14, 2013, 22:11

Malay,

Do you have a constant temperature value set for your inlet total temperature? If so, this may be a problem. For my inlet conditions, I imported a total temperature profile simulating a thermal boundary layer and this fixed the heat transfer spike at the inlet.

Best of luck!

flotus1 · March 15, 2013, 02:13

Try to untick the "node values" option for your plot.

November 3, 2012, 03:52		#13
A7A Member AHMAD Join Date: Apr 2012 Posts: 54 Rep Power: 0	The temperature of the channel base is decreasing, so Nu number must be increasing along the channel base, but Nu plot doesnt give you this result because of the jump of Nu number at the end of channel, so try to decrease the range of the Y-axis of the plot to see what is the real distribution of Nu number. malay likes this.

March 14, 2013, 22:11	Success!	#19
carlt336 New Member Matt Carlton Join Date: Feb 2012 Posts: 2 Rep Power: 0	Malay, Do you have a constant temperature value set for your inlet total temperature? If so, this may be a problem. For my inlet conditions, I imported a total temperature profile simulating a thermal boundary layer and this fixed the heat transfer spike at the inlet. Best of luck!

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October 29, 2012, 23:08		#2
malay Senior Member ahmad Join Date: Feb 2012 Posts: 101 Rep Power: 14	can somebody get me some help ??

October 30, 2012, 00:04		#3
A7A Member AHMAD Join Date: Apr 2012 Posts: 54 Rep Power: 0	Hi, What is the type of BC you gave to the base of the channel, is it heat flux or temperature?

October 30, 2012, 00:38		#4
sofie1 Member sofia Join Date: Apr 2010 Location: world Posts: 31 Rep Power: 16	Hi Is your geometry 2D or 3D

October 30, 2012, 09:30		#7
A7A Member AHMAD Join Date: Apr 2012 Posts: 54 Rep Power: 0	As the BC is heat flux, fluent will give you this result(constant heat flux), and if you want to check how the heat flux is changing along the channel base you have to use temperature as BC for the channel base.

October 30, 2012, 09:42		#9
A7A Member AHMAD Join Date: Apr 2012 Posts: 54 Rep Power: 0	I dont know why fluent give this jump, but have you checked the temperature variation along the channel base, and the heat transfer coefficient. If there isnt any thing wrong so it maybe something related to the nature of the mesh you are using.

October 30, 2012, 09:49		#11
A7A Member AHMAD Join Date: Apr 2012 Posts: 54 Rep Power: 0	could you put a picture of temperature and Nu plots.

November 7, 2012, 11:19		#15
A7A Member AHMAD Join Date: Apr 2012 Posts: 54 Rep Power: 0	Have you checked the reference values you are using like length and temperature.

March 7, 2013, 00:52		#17
carlt336 New Member Matt Carlton Join Date: Feb 2012 Posts: 2 Rep Power: 0	Malay, did you solve your problem with the heat transfer spikes at each end? I am having similar issues. Could it be a problem in the mesh?

March 15, 2013, 02:13		#20
flotus1 Super Moderator Alex Join Date: Jun 2012 Location: Germany Posts: 3,399 Rep Power: 46	Try to untick the "node values" option for your plot.