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Old   April 23, 2012, 15:17
Default Drag Coefficient
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Im trying to find the drag coefficient for NACA0012
Although I have a really fine mesh, it doesnt converge and at best it gives me 50% off the experimental data
why is it like this?
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Old   April 23, 2012, 22:58
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Quote:
Originally Posted by James Hetfield View Post
Im trying to find the drag coefficient for NACA0012
Although I have a really fine mesh, it doesnt converge and at best it gives me 50% off the experimental data
why is it like this?
You should focus on the problem of convergence beforehand. You shouldn't expect any meaningful results if the solution has not reached any type of convergence. If you give some details of how you're modelling it then maybe we can come up with reasons why it is not converging. Things like y+, turbulence models used, wall function approach, discretization scheme, etc etc. Give details if you want help!

If the solution had converged then I would have said, for Drag Coefficient

What is 50% off? Is it the drag coefficient?

Did you remember to set your reference values? You need to specify the reference density and velocity for the dragon coefficient. For force vector you also need to input the reference vector. Other coefficients use other reference values also.
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Old   April 24, 2012, 13:01
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although my mesh is fine (starts from 1e-06 normal to the airfoil surface) I dont reach convergence
what is wrong with it?
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Old   April 24, 2012, 16:45
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Quote:
Originally Posted by James Hetfield View Post
although my mesh is fine (starts from 1e-06 normal to the airfoil surface) I dont reach convergence
what is wrong with it?
Can you give any other details about the simulation? And wth is 1e06? How big is your airfoil? Anything? Give details!
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Old   April 24, 2012, 21:21
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1e0-6 is the distance of first layer from the airfoil
the chord is 1 meter

Im using C-mesh

Im trying to use SA or SST-KW for turbulence model but i cant get convergence

give me email so i cant send u "tin" file
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Old   April 24, 2012, 21:53
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Quote:
Originally Posted by James Hetfield View Post
1e0-6 is the distance of first layer from the airfoil
the chord is 1 meter

Im using C-mesh

Im trying to use SA or SST-KW for turbulence model but i cant get convergence

give me email so i cant send u "tin" file
1e-6 astronomical units?
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Old   April 24, 2012, 21:58
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1e-06 meter
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