# direction vectors for lift and drag for 3d wing

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 July 3, 2014, 13:55 direction vectors for lift and drag for 3d wing #1 Member   nauman hashmi Join Date: Jun 2012 Posts: 54 Rep Power: 10 in 2d aerofoil analysis the direction vectors of aoa are used to calculate lift and drag does the same hold good for 3d wing also? moreover for lift calculation a different area is required while for dag calculation a different area is required shud both be calculated separately in fluent?

July 4, 2014, 05:50
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Quote:
 Originally Posted by nauman55 in 2d aerofoil analysis the direction vectors of aoa are used to calculate lift and drag does the same hold good for 3d wing also? moreover for lift calculation a different area is required while for dag calculation a different area is required shud both be calculated separately in fluent?

For both lift and drag calculations use the projected area of your wing (projected in global roll and pitch axis (x-y)).
In Fluent you can specify your wing area in the Reference Values Tab and monitor your coefficients. Once you have coefficients you can calculate the force.

 July 4, 2014, 05:53 #3 Member   nauman hashmi Join Date: Jun 2012 Posts: 54 Rep Power: 10 mean if my geometry is in YZ plane then i have to take projected area of x axis and z axis add them and use them as reference?

July 4, 2014, 06:20
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Quote:
 Originally Posted by nauman55 mean if my geometry is in YZ plane then i have to take projected area of x axis and z axis add them and use them as reference?
Without a picture no one can answer you.

July 4, 2014, 06:27
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nauman hashmi
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 July 4, 2014, 06:44 #6 Member   Join Date: Mar 2014 Posts: 39 Rep Power: 8 Use the projected area of your wing in the x-y-plane to build coefficients. But if you just want to calculate forces you can also use the Reports Tab in Fluent (no wing area required). Just specify a direction vector and your parts / surfaces and Fluent will calculate the forces you want to know.

 July 4, 2014, 06:47 #7 Member   nauman hashmi Join Date: Jun 2012 Posts: 54 Rep Power: 10 sir flow direction is in y and z direction so should i use the z axis projected area and x axis projected or x and y axis?

 July 4, 2014, 07:02 #8 Member   Join Date: Mar 2014 Posts: 39 Rep Power: 8 I have absolutely no idea what you are trying to do - its not possible to project an area to an axis. You have to project the area to a plane - in your system to the xy plane (the plane normal to your z-axis).

 July 4, 2014, 07:12 #9 Member   nauman hashmi Join Date: Jun 2012 Posts: 54 Rep Power: 10 sir i am trying to calculate lift and drag coefficient for this configuration at mach 0.8 and 41000 feet altitude (cruise condition) i am using fluent in fluent i can find projected area in axis not in plane i hope i have made myself clear

 July 4, 2014, 07:22 #10 Member   Join Date: Mar 2014 Posts: 39 Rep Power: 8 ok. your first post says you want to calculate forces and not coefficients. use the projection direction z-axis. this will give you the projected area in the xy-plane you need for the coefficients.

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