# Lift and Drag Coefficients

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

 February 13, 2007, 05:27 Re: Lift and Drag Coefficients #2 Kasper Skriver Guest   Posts: n/a You will have to somehow extract the forces. Normal and tangential. Then you would be able to calculate the coefficients from projected areas.

 February 13, 2007, 06:14 Re: Lift and Drag Coefficients #3 xdm Guest   Posts: n/a Kasper, i know the theory! I just want to know the commands in pro-star!

 February 13, 2007, 06:18 Re: Lift and Drag Coefficients #4 Kasper Skriver Guest   Posts: n/a Ho much will you pay me then?

 February 13, 2007, 06:28 Re: Lift and Drag Coefficients #5 Kasper Skriver Guest   Posts: n/a In the star_uguide.pdf at page 9-26 7. Calculating aerodynamic coefficients â€" 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

 February 13, 2007, 14:50 Re: Lift and Drag Coefficients #6 paulh Guest   Posts: n/a 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.

 February 14, 2007, 09:19 Re: Lift and Drag Coefficients #7 Tobbe Guest   Posts: n/a 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+.

 April 8, 2007, 17:55 gambit modelling and fluent analysis of jeep #8 talha Guest   Posts: n/a i would like to know and recieve the 3D modelling and analysis of jeep using gambit and fluent.

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