Fluent- bad pressure contours and messages while calculating

tom634 · January 21, 2012, 08:15

Hello,
I make compressor simulations. K-epsilon, pressure based, gauge pressure and initial pressure at inlet 1bar, pressure outlet 2,5bar, walls of blades rotating 16.000rad/s, maximum cell squish 0,802, maximum cell skewness 0,88, maximum aspect ratio 22,5. I receive results as on picture:
http://i.imgur.com/nQYFJ.png
I have underpressure, solution doesn't converge, I receive all the time while calculating "Reversed flow in xxx faces on pressure inlet yy. Reversed flow in zzz faces on pressure outlet tt. Turbulent viscosity limited to viscosity ratio of 1e+5 in vvvvvv cells." event after 3000 iterations. When I take density based, I receive "Divergence detected in AMG Solver: Coupled -> Decreasing coarsening group size! Increasing relaxation sweeps! Reducing Courant number."
How to edit Cell-Zone Conditions? I have only fluid in cell-zone conditions.
What is wrong and how to repair this?

tom634 · January 22, 2012, 09:19

What do you suggest to do with this case? Max skew size is 0.85.
http://i.imgur.com/azUUj.png

cartman · February 1, 2012, 07:50

how was your under-relaxtion factors?

tom634 · February 1, 2012, 12:19

Standard, I didn't change anything. Problem solved by manipulating limits of pressure and temperature.

hadi1984 · March 6, 2013, 03:22

you mean it solved by pressure based method? or density based?

January 21, 2012, 08:15	Fluent- bad pressure contours and messages while calculating	#1
tom634 New Member Join Date: Apr 2011 Posts: 29 Rep Power: 15	Hello, I make compressor simulations. K-epsilon, pressure based, gauge pressure and initial pressure at inlet 1bar, pressure outlet 2,5bar, walls of blades rotating 16.000rad/s, maximum cell squish 0,802, maximum cell skewness 0,88, maximum aspect ratio 22,5. I receive results as on picture: http://i.imgur.com/nQYFJ.png I have underpressure, solution doesn't converge, I receive all the time while calculating "Reversed flow in xxx faces on pressure inlet yy. Reversed flow in zzz faces on pressure outlet tt. Turbulent viscosity limited to viscosity ratio of 1e+5 in vvvvvv cells." event after 3000 iterations. When I take density based, I receive "Divergence detected in AMG Solver: Coupled -> Decreasing coarsening group size! Increasing relaxation sweeps! Reducing Courant number." How to edit Cell-Zone Conditions? I have only fluid in cell-zone conditions. What is wrong and how to repair this? Last edited by tom634; January 21, 2012 at 09:59.

January 22, 2012, 09:19		#2
tom634 New Member Join Date: Apr 2011 Posts: 29 Rep Power: 15	What do you suggest to do with this case? Max skew size is 0.85. http://i.imgur.com/azUUj.png

February 1, 2012, 07:50		#3
cartman Member Chris, Kam Join Date: Nov 2010 Location: Busan, South Korea Posts: 42 Rep Power: 15	how was your under-relaxtion factors?

February 1, 2012, 12:19		#4
tom634 New Member Join Date: Apr 2011 Posts: 29 Rep Power: 15	Standard, I didn't change anything. Problem solved by manipulating limits of pressure and temperature.

March 6, 2013, 03:22		#5
hadi1984 New Member Hadi Join Date: May 2009 Posts: 7 Rep Power: 16	you mean it solved by pressure based method? or density based?