Fluent value vs UDF value discrepancy

argeus · May 27, 2011, 14:12

hello hello,
Any help highly appreciated.. please..

Im using a F_FLUX(t,tf) to extract data (mass flow rate) from fluent to a .txt file. x = F_FLUX (t,tf) access data from each elementary face. then I use a auxilliary variable, which sums the values from all elementary cells. looks like: y =+ x;. Now I have a total mass flow rate [kg/s] through a boundary face. But, when i try to compare this value with value accessible in Fluent reports >Report>Fluxes, or >Report>Surface integrals, I get a something totally different. I have no idea why..
Just for completness - simulation is unsteady, I just pick up some converged time step for confrontation..

Any idea? thank you very much in advance..

dmoroian · May 31, 2011, 05:06

Probably a typo: y =+ x
If you're using the above atribution with the intent of y = y+x; then is wrong. What it really means is: y = +x; or simpler y = x.

argeus · May 31, 2011, 15:08

no no, im sorry, just a typo.. i want to write y+=x..

May 27, 2011, 14:12	Fluent value vs UDF value discrepancy	#1
argeus New Member Ján Join Date: Mar 2010 Location: Slovakia Posts: 24 Rep Power: 16	hello hello, Any help highly appreciated.. please.. Im using a F_FLUX(t,tf) to extract data (mass flow rate) from fluent to a .txt file. x = F_FLUX (t,tf) access data from each elementary face. then I use a auxilliary variable, which sums the values from all elementary cells. looks like: y =+ x;. Now I have a total mass flow rate [kg/s] through a boundary face. But, when i try to compare this value with value accessible in Fluent reports >Report>Fluxes, or >Report>Surface integrals, I get a something totally different. I have no idea why.. Just for completness - simulation is unsteady, I just pick up some converged time step for confrontation.. Any idea? thank you very much in advance..

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
fluent udf, saving data in udf	mohsen zendehbad	Fluent UDF and Scheme Programming	15	June 14, 2017 00:23
Transient pressure UDF for parallel fluent	droberts	Fluent UDF and Scheme Programming	5	October 11, 2010 05:13
udf fluent 6.3.26 don't work in fluent 12	enry	Fluent UDF and Scheme Programming	16	September 9, 2010 03:44
Using Fluent with a UDF frm a remote m/c	aarti	FLUENT	2	September 11, 2008 20:53
Can somebody send me a Fluent 6 UDF manual??	KKLAU	FLUENT	4	April 14, 2004 17:37

May 31, 2011, 05:06		#2
dmoroian Senior Member Dragos Join Date: Mar 2009 Posts: 648 Rep Power: 20	Probably a typo: y =+ x If you're using the above atribution with the intent of y = y+x; then is wrong. What it really means is: y = +x; or simpler y = x.

May 31, 2011, 15:08		#3
argeus New Member Ján Join Date: Mar 2010 Location: Slovakia Posts: 24 Rep Power: 16	no no, im sorry, just a typo.. i want to write y+=x..