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3D Airfoil simualtion

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Old   October 15, 2015, 10:47
Exclamation 3D Airfoil simualtion
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I'm trying to simulate a 3D airfoil in fluent. I've done the meshing and have got 3 grids which I know will give me independency:
G1 - 636,000 elements
G2 - 890,400 elements
G3 - 1,272,000 elements

Reynolds no. is 120,000 and for turbulence I must use k-omega SST. I use COUPLED for coupling press. and vel. and for Pressure I use PRESTO! , for momentum QUICK , Turb. kinetic energy and press. diss. rate also 2nd order up wind.
it worked perfectly fine with around 270,000 elements. but the amount of Cl was not right and I needed to get mesh independency. I checked G1 but it diverges after 2 rounds. changed turb. kin. energy and press. diss. rate to QUICK but didn't change anything?
Can anyone help me and tell me what the problem is?
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Old   October 17, 2015, 18:53
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Hey I'm trying to understand how to properly simulate an airfoil in Fluent too. Exactly what aspects are you observing, and what's the speed and altitude? What made you choose your simulation method? Why is your mesh separated, and what kind of mesh is it?
Thanks.
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Old   October 18, 2015, 15:03
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you should check Cl and Cd convergence other than residuals. for setting the speed you should set in boundary condition. I chose the method because of the relatively high Reynolds no. and also read it in a paper. my mesh is a C Grid. I don't' really get what you mean by why is the mesh separated.
for more details check the link below
https://confluence.cornell.edu/displ...ver+an+Airfoil
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Old   October 18, 2015, 19:51
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As I'm quite new I can't really help you that much. What I can do is recommend the k epsilon model as it appears to be the most popular with the aerodynamics you're focusing on. The compressibility of your flow depends on what kind of flight you're looking at, if its subsonic consider incompressible. Convergence may be affected by your pressure velocity coupling (maybe PRESTO would be better?). If anyone has more experience in this they should jump in. Again, it'd be nice if you gave more detail as to what your target altitude and velocity are, as well as the characteristics you're identifying (flow on the wing, behind the wing, pressure, etc).

Last edited by Rarepepe; October 18, 2015 at 23:01.
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airfoil, airfoil 3d, divergence, mesh independence, mesh independency

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