What is mass imbalance?

thecfduser · December 6, 2009, 09:55

Hi all,
what is mass imbalance??? The finite volume method is not always conservative????? Is the imbalance due only to round off errors??
Thanks

Philipov · December 7, 2009, 02:17

There was such a topic.. try to search and find it

thecfduser · December 7, 2009, 15:03

Hi
in fact i searched a lot and found some topics, but none of it treats this particular question....They all say that FV are conservative wich is not the case of FD, but they never talk about mass imbalance..
Regards

ivanbuz · December 8, 2009, 01:38

from Fluent user guide

thecfduser · December 8, 2009, 02:56

Hello Ivan,
thank u a lot for ure help.
But i want to know if this imbalance or mass creation is only due to round off errors or not.....
Can this imbalance be cumulative??? so it can be important or always very small????

One more question please:
in the case that this imbalance can be huge, so why Finite volumes is alway prefered to Finite Difference or Finite elements???? All FV users tell because it conserves mass..

Thanks and regards

December 6, 2009, 09:55	What is mass imbalance?	#1
thecfduser Senior Member karine Join Date: Nov 2009 Posts: 158 Rep Power: 16	Hi all, what is mass imbalance??? The finite volume method is not always conservative????? Is the imbalance due only to round off errors?? Thanks

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
mass flow in is not equal to mass flow out	saii	CFX	12	March 19, 2018 05:21
Integral of mass Imbalance drops with time	TfG	FLUENT	0	April 3, 2009 11:38
Mass imbalance	Aly	FLUENT	7	October 6, 2004 21:07
OutletBoundary Condition Causes Mass Imbalance	Andy	Main CFD Forum	0	March 11, 2004 14:05
Residual Problem -Mass Imbalance	Jie	FLUENT	0	February 19, 2002 10:49

December 7, 2009, 02:17		#2
Philipov Senior Member Svetlin Filipov Join Date: Mar 2009 Location: United Kingdom Posts: 176 Rep Power: 17	There was such a topic.. try to search and find it

December 7, 2009, 15:03		#3
thecfduser Senior Member karine Join Date: Nov 2009 Posts: 158 Rep Power: 16	Hi in fact i searched a lot and found some topics, but none of it treats this particular question....They all say that FV are conservative wich is not the case of FD, but they never talk about mass imbalance.. Regards

December 8, 2009, 01:38		#4
ivanbuz Member Ivan Join Date: May 2009 Posts: 85 Rep Power: 16	from Fluent user guide

December 8, 2009, 02:56		#5
thecfduser Senior Member karine Join Date: Nov 2009 Posts: 158 Rep Power: 16	Hello Ivan, thank u a lot for ure help. But i want to know if this imbalance or mass creation is only due to round off errors or not..... Can this imbalance be cumulative??? so it can be important or always very small???? One more question please: in the case that this imbalance can be huge, so why Finite volumes is alway prefered to Finite Difference or Finite elements???? All FV users tell because it conserves mass.. Thanks and regards