UDF for temperature gradient

mariam.sara · March 24, 2013, 01:52

I have wall i need to apply the current equation as boundary to it:

k*dT/dy=dT/dy

where k thermal conductivity
T local temperature

how i can add it please ? did i need a UDF for it?

vasava · March 25, 2013, 06:36

Yes you do need UDF. I think you could use the 'DEFINE PROFILE' macro.

mvee · March 26, 2013, 02:27

Hi

You need to use DEFINE_ADJUST function to set C_T_G as zero on the wall of your interest which is called using LOOK_UP_THREAD.

Best wishes.
Mvee

mariam.sara · March 26, 2013, 16:00

what did you mean with C_T_G? can you write me the term and post me it here?

Quote:

Originally Posted by mvee

Hi

You need to use DEFINE_ADJUST function to set C_T_G as zero on the wall of your interest which is called using LOOK_UP_THREAD.

Best wishes.
Mvee

mvee · March 28, 2013, 00:02

C_T_G() - temperature gradient stored at cell locations. Please refer UDF manual.

amin_ghaemian · February 16, 2016, 16:13

C_T_G is used for compiling gradient over cells... but we need to calculate gradient over face thread!!!!!!!
so what we must to do???????

larry_lekwana · February 25, 2016, 08:03

Hi guys,

I am modelling a solid biomass combustion system using a transient, Eulerian multi-phase model in conjunction with a species transport model. I need to write a DEFINE_MASS_TRANSFER udf in order to determine the thermally driven rate of drying of the solid fuel. This requires the the determination of the time derivative of the particle temperature, which I do not know how to code. Please can someone help?

Thank you guys in advance for your assistance.

Saman95 · March 7, 2018, 11:57

Quote:

Originally Posted by amin_ghaemian

C_T_G is used for compiling gradient over cells... but we need to calculate gradient over face thread!!!!!!!
so what we must to do???????

hello i have same problem

What did u do for this?

please help me

thanks

mvee · March 7, 2018, 22:01

Find out the cell temperature on left and right side of the face. Take difference and divide by its distance. You will need faceloop and cell loop. Hope this helps.

March 24, 2013, 01:52	UDF for temperature gradient	#1
mariam.sara Senior Member Join Date: Jan 2011 Posts: 339 Rep Power: 16	I have wall i need to apply the current equation as boundary to it: k*dT/dy=dT/dy where k thermal conductivity T local temperature how i can add it please ? did i need a UDF for it?

February 25, 2016, 08:03	Temporal temperature derivative mass transfer udf	#7
larry_lekwana New Member Larry Lekwana Join Date: Feb 2016 Posts: 1 Rep Power: 0	Hi guys, I am modelling a solid biomass combustion system using a transient, Eulerian multi-phase model in conjunction with a species transport model. I need to write a DEFINE_MASS_TRANSFER udf in order to determine the thermally driven rate of drying of the solid fuel. This requires the the determination of the time derivative of the particle temperature, which I do not know how to code. Please can someone help? Thank you guys in advance for your assistance.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Wall shear stress gradient udf	Andrew	FLUENT	3	April 4, 2018 02:36
The gradient of void fraction in UDF	summer	FLUENT	2	May 20, 2011 04:34
UDF temp gradient tutotial	tejasvikrishna	FLUENT	0	April 4, 2011 12:10
UDF sample for velocity gradient	J.Y.Shin	FLUENT	2	January 19, 2007 19:04
Gradient in UDF	summer	FLUENT	0	September 1, 2006 14:50

March 25, 2013, 06:36		#2
vasava Senior Member Paritosh Vasava Join Date: Oct 2012 Location: Lappeenranta, Finland Posts: 732 Rep Power: 23	Yes you do need UDF. I think you could use the 'DEFINE PROFILE' macro.

March 26, 2013, 02:27		#3
mvee Senior Member Vaze Join Date: Jun 2009 Posts: 172 Rep Power: 17	Hi You need to use DEFINE_ADJUST function to set C_T_G as zero on the wall of your interest which is called using LOOK_UP_THREAD. Best wishes. Mvee

March 28, 2013, 00:02		#5
mvee Senior Member Vaze Join Date: Jun 2009 Posts: 172 Rep Power: 17	C_T_G() - temperature gradient stored at cell locations. Please refer UDF manual.

February 16, 2016, 16:13		#6
amin_ghaemian New Member amin ghaemian Join Date: Nov 2015 Posts: 1 Rep Power: 0	C_T_G is used for compiling gradient over cells... but we need to calculate gradient over face thread!!!!!!! so what we must to do???????

March 7, 2018, 22:01		#9
mvee Senior Member Vaze Join Date: Jun 2009 Posts: 172 Rep Power: 17	Find out the cell temperature on left and right side of the face. Take difference and divide by its distance. You will need faceloop and cell loop. Hope this helps.