wrong pressure contour

Fasouras · July 12, 2018, 07:38

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)

Leonardo.flores · July 13, 2018, 04:49

Would be interesting to see those velocity and pressure contours.

Fasouras · July 13, 2018, 11:20

of course

thank you for your response

LuckyTran · July 13, 2018, 11:36

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?

Leonardo.flores · July 13, 2018, 14:10

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.

Fasouras · July 14, 2018, 09:09

Quote:

Originally Posted by Leonardo.flores

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 !!!!

July 12, 2018, 07:38	wrong pressure contour	#1
Fasouras New Member Greece Join Date: May 2017 Posts: 20 Rep Power: 9	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)

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Wind tunnel Boundary Conditions in Fluent	metmet	FLUENT	6	October 30, 2019 13:23
Periodic flow using Cyclic - comparison with Fluent	nusivares	OpenFOAM Running, Solving & CFD	30	December 12, 2017 06:35
Discharge of Pressure Vessel into Pipe with Regulator	gajowni2	System Analysis	0	October 31, 2015 19:57
what the result is negatif pressure at inlet	chong chee nan	FLUENT	0	December 29, 2001 06:13
Hydrostatic pressure in 2-phase flow modeling (long)	DS & HB	Main CFD Forum	0	January 8, 2000 16:00

July 13, 2018, 04:49		#2
Leonardo.flores Member Leonardo Join Date: Nov 2017 Posts: 37 Rep Power: 9	Would be interesting to see those velocity and pressure contours.

July 13, 2018, 11:36		#4
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,754 Rep Power: 66	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?

July 13, 2018, 14:10		#5
Leonardo.flores Member Leonardo Join Date: Nov 2017 Posts: 37 Rep Power: 9	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.