Natural Convection

santamary · July 28, 2009, 23:29

i want simulation natural convection loop by FLUENT but i have some problem.
my result depend on intitial value?!!!

What do i?

ericguangzhou · July 29, 2009, 10:28

Did you Set air density to be constant?

santamary · July 30, 2009, 03:16

working fluid is water & i use Boussinesq approximation for density

Chris D · July 30, 2009, 15:26

What do you mean when you say that your result depends on your initial value? Do you mean that you get a different result if you initialize your solution with different values for velocity?

santamary · August 1, 2009, 00:56

yes, if i put 300K for initial temperature i get in result (in temperature contour) 300k and if i put 320K for it i get 320

Chris D · August 1, 2009, 14:44

Have you checked the section in the FLUENT manual about natural convection to see if you have setup your simulation correctly? From what you are saying, it sounds like the temperature everywhere in the flow field is the same, meaning that there is probably something wrong with your setup. If in fact that's not what you're saying, could you please provide more information about your problem?

santamary · August 2, 2009, 03:32

i'm working in natural convection loop.

The heat sink is located at an elevation higher than the source. That causes the circulating fluid, heated from bottom and cooled
from top, to flow under the influence of gravity, the difference
in fluid density between the two vertical arms being the driving

force.
heater(heat source) expose constant thermal flux and cooler(heat sink) exposed costant temperature.working fluid is water.

santamary · August 4, 2009, 23:26

is there anyone?

July 28, 2009, 23:29	Natural Convection	#1
santamary New Member Maryam Kia shemshaki Join Date: Jul 2009 Posts: 5 Rep Power: 16	i want simulation natural convection loop by FLUENT but i have some problem. my result depend on intitial value?!!! What do i?

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July 29, 2009, 10:28		#2
ericguangzhou New Member zhangming Join Date: Jul 2009 Posts: 3 Rep Power: 16	Did you Set air density to be constant?

July 30, 2009, 03:16		#3
santamary New Member Maryam Kia shemshaki Join Date: Jul 2009 Posts: 5 Rep Power: 16	working fluid is water & i use Boussinesq approximation for density

July 30, 2009, 15:26		#4
Chris D Senior Member Chris Join Date: Jul 2009 Location: Ohio, USA Posts: 169 Rep Power: 16	What do you mean when you say that your result depends on your initial value? Do you mean that you get a different result if you initialize your solution with different values for velocity?

August 1, 2009, 00:56		#5
santamary New Member Maryam Kia shemshaki Join Date: Jul 2009 Posts: 5 Rep Power: 16	yes, if i put 300K for initial temperature i get in result (in temperature contour) 300k and if i put 320K for it i get 320

August 1, 2009, 14:44		#6
Chris D Senior Member Chris Join Date: Jul 2009 Location: Ohio, USA Posts: 169 Rep Power: 16	Have you checked the section in the FLUENT manual about natural convection to see if you have setup your simulation correctly? From what you are saying, it sounds like the temperature everywhere in the flow field is the same, meaning that there is probably something wrong with your setup. If in fact that's not what you're saying, could you please provide more information about your problem?

August 2, 2009, 03:32		#7
santamary New Member Maryam Kia shemshaki Join Date: Jul 2009 Posts: 5 Rep Power: 16	i'm working in natural convection loop. The heat sink is located at an elevation higher than the source. That causes the circulating fluid, heated from bottom and cooled from top, to flow under the influence of gravity, the difference in fluid density between the two vertical arms being the driving force. heater(heat source) expose constant thermal flux and cooler(heat sink) exposed costant temperature.working fluid is water.

August 4, 2009, 23:26		#8
santamary New Member Maryam Kia shemshaki Join Date: Jul 2009 Posts: 5 Rep Power: 16	is there anyone?