# Lift Coefficient

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 December 20, 2016, 03:58 Lift Coefficient #1 New Member   Anonymous Join Date: Nov 2016 Posts: 4 Rep Power: 9 Hello STAR group, I am doing an unsteady RANS simulation for a university assignment and I my aim is to calculate the lift and drag coefficients over a delta-type hydrofoil. The force coefficient reports appear to be influenced by an arbitrary area value. For the lift and drag coefficients I was thinking to use the projected area of the hydrofoil (in the cross-stream and stream directions respectively). Would it be more suitable to just use the actual area of the hydrofoil in both cases? Also, I am using symmetry to analyse only half the geometry and I was wondering whether the force coefficients should be eventually doubled to be representative of the full geometry. Many thanks, E

December 20, 2016, 20:18
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Quote:
 Originally Posted by Eli Gali For the lift and drag coefficients I was thinking to use the projected area of the hydrofoil (in the cross-stream and stream directions respectively). Would it be more suitable to just use the actual area of the hydrofoil in both cases?
It's a reference area, it really doesn't matter. The general convention for lifting surfaces is to use the planform area (so projected wing area on the ground) but if it's a hydrofoil they may have another convention.

Quote:
 Originally Posted by Eli Gali Also, I am using symmetry to analyse only half the geometry and I was wondering whether the force coefficients should be eventually doubled to be representative of the full geometry.
If you have half the force and you use half the reference area, the coefficient will be identical to all of the force and all of the area. So if you use the full area for half the force you need to double. Otherwise no.

 December 21, 2016, 01:28 #3 New Member   Anonymous Join Date: Nov 2016 Posts: 4 Rep Power: 9 Many thanks!

 Tags force coefficients, star-ccm+ 10.04, symmetry