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wrong pressure contour

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Old   July 12, 2018, 07:38
Unhappy wrong pressure contour
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Greece
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Hi



I am conducting a 2d airfoil analysis on a naca0015. i am using standard k-e model, water as material and i am doing it for a number of angle of attacks (0,2,4,6,8). I am changing the angle of attack as phrased below:
in boundary conditions --> inlet--> i choose components an the where x--> vcos(aoa) and where y--> vsin(aoa) (where v equals the speed,10.29 m/s)



also in monitor cd and cl:


cd: x-->cos(aoa) cl: x--> -sin(aoa)

y-->sin(aoa) y--> cos(aoa)


and i proceed like this changing aoas and changing models of turbulence.
The cl and cd seem legit from the results, but when i open cfd post, while the velocity seems legit and higher on the upper surface as supposed, the pressure seems wrongly higher again on the upper surface.



Does any of you guys has any theory, or a link to a post i might have missed?


Thanks in advance!



(btw this research is being done to decide the right airfoil to be attached to a sailing hydrofoil)
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Old   July 13, 2018, 04:49
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Would be interesting to see those velocity and pressure contours.
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Old   July 13, 2018, 11:20
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of course


thank you for your response
Attached Images
File Type: png velocity.PNG (117.0 KB, 14 views)
File Type: jpg pressure.jpg (156.4 KB, 15 views)
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Old   July 13, 2018, 11:36
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Why you have lines that look like streamlines in a pressure contour? My guess is you click some funny buttons and did not actually make a pressure contour.


Can you check directly in Fluent (and not CFD-post or whatever this is) what the pressure contour is?
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Old   July 13, 2018, 14:10
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I see what is wrong. Your location is "airfoil", so you are graphing the pressure in the edges of the airfoil. Change it to "Symmetry", so you can see the countours of all the domain. Also, you maybe have a streamline activated graphing the velocity, that is why it is higher at the top of the airfoil.
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Old   July 14, 2018, 09:09
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Quote:
Originally Posted by Leonardo.flores View Post
I see what is wrong. Your location is "airfoil", so you are graphing the pressure in the edges of the airfoil. Change it to "Symmetry", so you can see the countours of all the domain. Also, you maybe have a streamline activated graphing the velocity, that is why it is higher at the top of the airfoil.
thank you very much !!!!
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