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Lift and Drag Coefficients

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Old   February 12, 2007, 11:36
Default Lift and Drag Coefficients
  #1
xdm
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Hi guys, can you tell me the way to calculate lift and drag coefficients for a wing with star cd.

Thanks
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Old   February 13, 2007, 05:27
Default Re: Lift and Drag Coefficients
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Kasper Skriver
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You will have to somehow extract the forces. Normal and tangential. Then you would be able to calculate the coefficients from projected areas.

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Old   February 13, 2007, 06:14
Default Re: Lift and Drag Coefficients
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xdm
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Kasper, i know the theory! I just want to know the commands in pro-star!
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Old   February 13, 2007, 06:18
Default Re: Lift and Drag Coefficients
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Kasper Skriver
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Ho much will you pay me then?

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Old   February 13, 2007, 06:28
Default Re: Lift and Drag Coefficients
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Kasper Skriver
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In the star_uguide.pdf at page 9-26

7. Calculating aerodynamic coefficients " command ACOEFF.

This facility works in conjunction with values of total force components at the wall, loaded via the Wall Post Data dialog. A set of wall shells, enveloping the object whose coefficients are to be calculated, must also be created using a CSET operation.

a) add some shells on the wall boundary

b) do some wall post data

c) command acoeff, try help acoeff

d) pay my bills

BR and hope its working

Kasper Skriver
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Old   February 13, 2007, 14:50
Default Re: Lift and Drag Coefficients
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paulh
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You might also try to use 'Monitor Boundary Behavior' and export the forces per iteration. At the end of the analysis, import the text file into your favorite spreadsheet and do the math to get Cd & Cl. I would use this to judge convergence. I don't have any experience with wings, but for pass cars and heavy vehicles, drag settles down significantly after the residuals flatten out. However, use the acoef command for the final value. Although the trends are correct, there seems to be a problem with the absolute values coming out the boundary monitoring routines.
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Old   February 14, 2007, 09:19
Default Re: Lift and Drag Coefficients
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Tobbe
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CD-Adapco have a posdat subroutine for monitoring drag and lift. If you ask nicely they will probably give it to you for free. Otherwise, if its only drag and lift you are interested in and the geometry just is a simple wing, I would recomend using Star CCM+ instead, its much easier to monitor drag and lift in CCM+.
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Old   April 8, 2007, 17:55
Default gambit modelling and fluent analysis of jeep
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talha
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i would like to know and recieve the 3D modelling and analysis of jeep using gambit and fluent.
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