Flow simulation for an aerofoil

antm324 · April 22, 2015, 12:56

Hi guys,

I been running SolidWorks flow simulations for a naca0012 aerofoil, generally the CL is quite accurate to experimental data, but then suddenly it under predicts the stall angle by 4 degrees

does anybody know the cause of this?

also the CD is over predicted, is this down to the amount of refinement on the boundary layers?, there is 3 refinement levels and the flow is laminar and turbulent.

the results are being converged for Fx and Fy

so far i have received a lot more accurate results using fluent, why is this the case?

many thanks
Anthony

Chris_321 · April 22, 2015, 17:49

can you make a picture of your mesh and domain?

antm324 · April 22, 2015, 18:06

unfortunately i am not a a PC with SolidWorks at the moment, and thus only have screenshots taken with none being of the actual mesh

I was thinking the problem could be down to the k-epsilon code not modelling boundary layer correctly?

Chris_321 · April 22, 2015, 18:19

I had the same issues with FloEFD once, in my opinion the programm can not use the key advantages it has in simulations like that. But it should be possible to get closer to the experimental data.

Some things you could try:

Expand the domain in the wake of the airfoil, and shorten it in front of the profile a little bit. Maybe that can help.

You can try to improve your mesh even more with the manuel settings. For that turn of the "automatic" settings and improve the partial cells refinement.

antm324 · April 22, 2015, 18:25

my results at least for the Cl are not to bad apart from the stalling angle, and drag seems to be much worse. i was just interested to know the limitations of the software in external simulations. i have attached the results of these comparing them to experiemental data

Chris_321 · April 24, 2015, 04:55

Try to improve your partial cells, they are very important for the boundary layer of the immersed boundary approach that floefd uses to calculate the values near the wall. You need to control your mesh by hand not with the automatic settings to do that.

genom92 · May 12, 2015, 12:27

hey man, i'm currently doing the same thing as you. i'm doing the validation problem on naca0012 airfoil using solidworks.

your results seems better that mine though. can you attach the solidworks document. i would like to compare my setup and yours..

thanks..

antm324 · May 26, 2015, 13:19

Hey Fadli,

I do not wish to share files over the internet for the off-chance that these files could be found on turn-it in and have an effect on my grading for my dissertation. If you provide more in depth detail about your project and the options current chosen i would be happy to help.

Boris_M · July 13, 2015, 09:04

The Software can give much more accurate results if the mesh settings are right.
This was shown in a range of validations with many airfoils and full aircrafts such as from the Drag Prodiction Workshop.

Please send me your email address in a private message and I can send you a best practice guide in which there are also 3 validation models described.

Boris

April 22, 2015, 12:56	Flow simulation for an aerofoil	#1
antm324 New Member Anthony McCarthy Join Date: Nov 2014 Location: United Kingdom Posts: 21 Rep Power: 11	Hi guys, I been running SolidWorks flow simulations for a naca0012 aerofoil, generally the CL is quite accurate to experimental data, but then suddenly it under predicts the stall angle by 4 degrees does anybody know the cause of this? also the CD is over predicted, is this down to the amount of refinement on the boundary layers?, there is 3 refinement levels and the flow is laminar and turbulent. the results are being converged for Fx and Fy so far i have received a lot more accurate results using fluent, why is this the case? many thanks Anthony

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April 22, 2015, 17:49		#2
Chris_321 Member Christian Join Date: Sep 2013 Location: Germany Posts: 88 Rep Power: 12	can you make a picture of your mesh and domain?

April 22, 2015, 18:19		#4
Chris_321 Member Christian Join Date: Sep 2013 Location: Germany Posts: 88 Rep Power: 12	I had the same issues with FloEFD once, in my opinion the programm can not use the key advantages it has in simulations like that. But it should be possible to get closer to the experimental data. Some things you could try: Expand the domain in the wake of the airfoil, and shorten it in front of the profile a little bit. Maybe that can help. You can try to improve your mesh even more with the manuel settings. For that turn of the "automatic" settings and improve the partial cells refinement.

April 24, 2015, 04:55		#6
Chris_321 Member Christian Join Date: Sep 2013 Location: Germany Posts: 88 Rep Power: 12	Try to improve your partial cells, they are very important for the boundary layer of the immersed boundary approach that floefd uses to calculate the values near the wall. You need to control your mesh by hand not with the automatic settings to do that.

May 12, 2015, 12:27		#7
genom92 New Member fadli Join Date: May 2015 Location: Malaysia Posts: 8 Rep Power: 10	hey man, i'm currently doing the same thing as you. i'm doing the validation problem on naca0012 airfoil using solidworks. your results seems better that mine though. can you attach the solidworks document. i would like to compare my setup and yours.. thanks..

May 26, 2015, 13:19		#8
antm324 New Member Anthony McCarthy Join Date: Nov 2014 Location: United Kingdom Posts: 21 Rep Power: 11	Hey Fadli, I do not wish to share files over the internet for the off-chance that these files could be found on turn-it in and have an effect on my grading for my dissertation. If you provide more in depth detail about your project and the options current chosen i would be happy to help.

July 13, 2015, 09:04		#9
Boris_M Disabled Join Date: Jul 2009 Posts: 616 Rep Power: 23	The Software can give much more accurate results if the mesh settings are right. This was shown in a range of validations with many airfoils and full aircrafts such as from the Drag Prodiction Workshop. Please send me your email address in a private message and I can send you a best practice guide in which there are also 3 validation models described. Boris