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Old   October 24, 2010, 04:26
Default Lift distribution
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PB4
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Hi there,

I am fairly new to CFD so please be nice
I am looking to plot lift distribution over my wing, to help me predict initial spanwise stall point so I can adjust wing parameters (mainly twist and tip airfoil characteristics, the rest is fixed), the reason I want to use CFD as opposed to other well documented methods is that my wing is quite "dirty", I have 3 engine nacelles on the leading edge and a retractable float which fits under the wing at about 60% span though not flush with the surface, all that I'm sure will affect the results.
my questions are :
- How do I plot lift distribution along span ? I've played around with overall wing lift coef and section pressure coefs but would like to see some kind of spanwise lift curve, local Cl etc
- What would typically be mesh requirements for "good enough" spanwise lift distribution results ? I'm not looking into accurate drag or even lift values, just the distribution of it.

thanks all for your help !
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Old   October 28, 2010, 06:59
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Thomas Larsen
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Split the surface up in a upper and lower wing. Make an X-Y plot and plot Span - Pressure. Later you should export the file and do a regression analysis in your preffered data manager (Igor or etc..).

There is no good answer to what is fine enough mesh, but you should check that the Wall y+ values are within the correct value for the turbulence modle you are using. An general answer is that the more complex geometry requires finer mesh.
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Old   May 27, 2016, 04:56
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Quote:
Originally Posted by Larsen View Post
Split the surface up in a upper and lower wing. Make an X-Y plot and plot Span - Pressure. Later you should export the file and do a regression analysis in your preffered data manager (Igor or etc..).

There is no good answer to what is fine enough mesh, but you should check that the Wall y+ values are within the correct value for the turbulence modle you are using. An general answer is that the more complex geometry requires finer mesh.
Hi Thomas, I am having the same issue as well. Could you please explain a little bit more detail on how to split the surface? Thank you very much.
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Old   May 27, 2016, 14:36
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Matt
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Tip: Rather than comment on 6 year old threads asking for help, you should post a new thread.

To answer your question, it really depends on your input geometry. Can you give some clues as to how your wing is modeled?
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Old   May 28, 2016, 12:25
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Originally Posted by MBdonCFD View Post
Tip: Rather than comment on 6 year old threads asking for help, you should post a new thread.

To answer your question, it really depends on your input geometry. Can you give some clues as to how your wing is modeled?
Hey thanks for the advice. =)
I have attached the image in the design modeler. Fyi, I used half model to analyse the aircraaft and now I need to find out the lift distribution curve along the wingspan of my aircraft. Do you have any idea on this?
Attached Images
File Type: png design modeller.png (17.4 KB, 3 views)
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Old   May 31, 2016, 09:20
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You should post this question in an ANSYS forum. You will get better responses. This is a Star-CCM forum.

http://www.cfd-online.com/Forums/ansys/

I am not sure on how to approach this in ansys, but in Star-CCM I would either divide the surfaces up into a series of spanwise sections before meshing/running then extracting surface forces for each or define some probe points where you can get static pressure distributions at various locations along the span and integrate to get lift.
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Old   May 31, 2016, 09:46
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Quote:
Originally Posted by MBdonCFD View Post
You should post this question in an ANSYS forum. You will get better responses. This is a Star-CCM forum.

http://www.cfd-online.com/Forums/ansys/

I am not sure on how to approach this in ansys, but in Star-CCM I would either divide the surfaces up into a series of spanwise sections before meshing/running then extracting surface forces for each or define some probe points where you can get static pressure distributions at various locations along the span and integrate to get lift.
oic..thanks MBdon, I am fairly new here. I will post my problem there. Again, thanks for your help.
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