2D Axisymmetric vs. 3D
I am running a drag study on a shape that is essentially a revolved airfoil. As a test, I ran this shape in a 3D case then to cut down on computational time, I ran it in an antisymmetric 2D case. Problem is that the antisymmetric 2D case yields a drag which is nearly three times that of the 3D case (0.06lbf as compared to 0.18lbf). My tests are being performed at low velocities (30fps). I realize that with this little amount of information it is impossible for anyone to give me a definitive cause, but I was curious if this much variation is to be expected with such a low velocity, Reynolds Number, and drag, and if so, which calculation is more likely to be closer to the actual physical case. Thank you for any insight you can provide.
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axisymmetric gives you results as it should be in 3d.
* Is your 3d-model a full one, or did you use symmetric planes? * Did you give same BC in 2d as in 3d? compare the massflow-rates between 3d and 2d-axi |
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