Monitors for velocity

fbarbano · January 31, 2016, 09:33

Hello all,

I'm performing a CFD analysis with fluen that concern a natural convection cavity with air inside.

Obviously i have some problem of convergence and I don't kow how to decide to stop my calculation because the residual are not very stable. Better, they reach a condition of convergence but not stability.

So I think to put some monitors during the calculation. Until now I make ad average surface monitor on temperature and one on total heat flux but I'd like to be sure that also the velocity in converged and stable. So anybody has any advice about velocity monitors? For exemple mass average or integrals...

Many thank in advance to those who will respond.
Federico

Noobism · January 31, 2016, 11:05

If u feel that the iterations need run further, u can always lower the convergance limits for the residuals that show converging behaviour

fbarbano · January 31, 2016, 12:12

I altready turn off the default convergence limits of fluent but I need a monitor whom help me to control not the convergence and the stability.
This due to the intrinsic instability of the natural convection phenomena.

chrisf90 · February 22, 2016, 14:46

Hi,

In my studies I monitor velocity as area-weighted-average. As I am also quite new to Fluent I don't know if it is an appropriate way to do this. What I can tell you is that these Monitors reach a stable level after some iterations.

I also faced some convergence problems with natural convection problems. As I read in this forum and also noticed myself they can be very tricky sometimes.

regards
Chris

January 31, 2016, 09:33	Monitors for velocity	#1
fbarbano New Member Join Date: Nov 2015 Posts: 3 Rep Power: 10	Hello all, I'm performing a CFD analysis with fluen that concern a natural convection cavity with air inside. Obviously i have some problem of convergence and I don't kow how to decide to stop my calculation because the residual are not very stable. Better, they reach a condition of convergence but not stability. So I think to put some monitors during the calculation. Until now I make ad average surface monitor on temperature and one on total heat flux but I'd like to be sure that also the velocity in converged and stable. So anybody has any advice about velocity monitors? For exemple mass average or integrals... Many thank in advance to those who will respond. Federico

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January 31, 2016, 11:05		#2
Noobism New Member Rajat Join Date: Dec 2015 Posts: 4 Rep Power: 10	If u feel that the iterations need run further, u can always lower the convergance limits for the residuals that show converging behaviour

January 31, 2016, 12:12		#3
fbarbano New Member Join Date: Nov 2015 Posts: 3 Rep Power: 10	I altready turn off the default convergence limits of fluent but I need a monitor whom help me to control not the convergence and the stability. This due to the intrinsic instability of the natural convection phenomena.

February 22, 2016, 14:46		#4
chrisf90 New Member Christoph Ferk Join Date: Feb 2016 Posts: 17 Rep Power: 10	Hi, In my studies I monitor velocity as area-weighted-average. As I am also quite new to Fluent I don't know if it is an appropriate way to do this. What I can tell you is that these Monitors reach a stable level after some iterations. I also faced some convergence problems with natural convection problems. As I read in this forum and also noticed myself they can be very tricky sometimes. regards Chris