Question for 2D airfoil simulation

Roland R · September 28, 2011, 08:54

Hello,

In some cases I detect in my 2D simulations the next notice in convergence history:

U-Mom | 1.01 | 3.5E-06 | 7.4E-05 | 3.8E-05 OK
V-Mom | 1.00 | 2.8E-07 | 4.7E-06 | 1.0E-04 OK
W-Mom | 0.93 | 2.2E-29 | 1.6E-27 | 7.7E+11 *
P-Mass | 1.01 | 7.9E-09 | 2.2E-07 | 44.0 8.7E-01 ok

Based on the CFD online help:

"For the planar mesh the extrusion should be approximately equal to the smallest element edge length"

The mesh in my simulation is proper for this condition. Inspite of this the W-Mom is not OK. (Direction W is normal to the symmetry plane.)

What does it mean? How can I help the calculation?

Thanks
Roland

ghorrocks · September 28, 2011, 09:43

The linear solver is not happy, but the residuals are very low. If it proceeds and converges with the other equations I would ignore it.

Roland R · September 28, 2011, 10:49

Quote:

Originally Posted by ghorrocks

The linear solver is not happy, but the residuals are very low. If it proceeds and converges with the other equations I would ignore it.

Based on the results your suggestion is correct really. By the way the * turned into OK after ~200 iterations.

September 28, 2011, 08:54	Question for 2D airfoil simulation	#1
Roland R Senior Member Roland Rakos Join Date: Mar 2009 Posts: 131 Rep Power: 17	Hello, In some cases I detect in my 2D simulations the next notice in convergence history: U-Mom \| 1.01 \| 3.5E-06 \| 7.4E-05 \| 3.8E-05 OK V-Mom \| 1.00 \| 2.8E-07 \| 4.7E-06 \| 1.0E-04 OK W-Mom \| 0.93 \| 2.2E-29 \| 1.6E-27 \| 7.7E+11 * P-Mass \| 1.01 \| 7.9E-09 \| 2.2E-07 \| 44.0 8.7E-01 ok Based on the CFD online help: "For the planar mesh the extrusion should be approximately equal to the smallest element edge length" The mesh in my simulation is proper for this condition. Inspite of this the W-Mom is not OK. (Direction W is normal to the symmetry plane.) What does it mean? How can I help the calculation? Thanks Roland

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September 28, 2011, 09:43		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	The linear solver is not happy, but the residuals are very low. If it proceeds and converges with the other equations I would ignore it.