Natural convection energy convergence problem

sanooj · October 27, 2015, 05:23

Hi....
Am working now on a Natural Convection of Vertical fin arrays(vertical plate, horizontal fin surface) problem.The thing is that my Energy Equation isn,t converging!...

devesh.baghel · October 27, 2015, 07:19

Can you please elaborate more on problem statement/case setup ?

Devesh

LuckyTran · October 27, 2015, 11:15

Is it diverging or is it not converging?

Assuming you did everything correctly (beautiful mesh, correct boundary conditions, strong initial guess, etc). Lowering the urf to 0.5 for energy helps if it's a coupling problem that's preventing your solution from converging.

Are you using boussinesq, ideal gas, or real gas? An ideal gas / real gas needs a very good initial guess or it's most likely to diverge on the first iteration. What about other properties? Are they constants or fully implicit?

Anyway there's not enough information given to have any meaningful discussion of what is occurring.

sanooj · October 27, 2015, 11:49

Quote:

Originally Posted by devesh.baghel

Can you please elaborate more on problem statement/case setup ?

Devesh

hi devesh..
http://www.cfd-online.com/Forums/att...1&d=1445964513

please check this
in this i have given a,b,f as air inlets...with velocity 0.1m/s.heat flux was given at fin base plate and pressure outlet on faces e and c.
here gravity waz on at 9.81m/s2

used bussiness approximation,solution method- SIMPLEC,pressure-body weighed and momentum,energy as power law...
my energy is nt converging.....do help me..

sanooj · October 27, 2015, 11:55

please check this....
in this i have given a,b,f as air inlets...with velocity 0.1m/s.heat flux was given at fin base plate and pressure outlet on faces e and c.
here gravity waz on at 9.81m/s2

used bussiness approximation,solution method- SIMPLEC,pressure-body weighed and momentum,energy as power law...
my energy is nt converging.....do help me..

Capture.PNG

devesh.baghel · October 29, 2015, 07:23

Hi,

Can you please post convection current contour plot ?
Did you try with lower URF of energy as Lucky suggested ?

Also look for, top surface (Pressure-outlet) should bound the flow field in current domain.

October 27, 2015, 05:23	Natural convection energy convergence problem	#1
sanooj New Member SANOOJ SIDDIKH Join Date: Oct 2015 Posts: 3 Rep Power: 10	Hi.... Am working now on a Natural Convection of Vertical fin arrays(vertical plate, horizontal fin surface) problem.The thing is that my Energy Equation isn,t converging!...

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October 27, 2015, 07:19		#2
devesh.baghel Member Devesh Baghel Join Date: Mar 2009 Posts: 84 Rep Power: 17	Can you please elaborate more on problem statement/case setup ? Devesh

October 27, 2015, 11:15		#3
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,674 Rep Power: 66	Is it diverging or is it not converging? Assuming you did everything correctly (beautiful mesh, correct boundary conditions, strong initial guess, etc). Lowering the urf to 0.5 for energy helps if it's a coupling problem that's preventing your solution from converging. Are you using boussinesq, ideal gas, or real gas? An ideal gas / real gas needs a very good initial guess or it's most likely to diverge on the first iteration. What about other properties? Are they constants or fully implicit? Anyway there's not enough information given to have any meaningful discussion of what is occurring.

October 27, 2015, 11:55		#5
sanooj New Member SANOOJ SIDDIKH Join Date: Oct 2015 Posts: 3 Rep Power: 10	please check this.... in this i have given a,b,f as air inlets...with velocity 0.1m/s.heat flux was given at fin base plate and pressure outlet on faces e and c. here gravity waz on at 9.81m/s2 used bussiness approximation,solution method- SIMPLEC,pressure-body weighed and momentum,energy as power law... my energy is nt converging.....do help me.. Capture.PNG

October 29, 2015, 07:23		#6
devesh.baghel Member Devesh Baghel Join Date: Mar 2009 Posts: 84 Rep Power: 17	Hi, Can you please post convection current contour plot ? Did you try with lower URF of energy as Lucky suggested ? Also look for, top surface (Pressure-outlet) should bound the flow field in current domain.