Lift and Drag

Kimican · July 1, 2015, 11:03

Hi guys,

i want to calculate lift and drag forces and their coefficients for an airfoil.. i will use SST for turbulence model but i do not know how can i calculate lift and drag.. i request your suggestions.. Thank you..

antm324 · July 2, 2015, 13:10

What Software are you using? If your are using fluent you have ?two? options:

1) You can use the Cl & Cd monitors, under the monitor tab in the solution section, here you can create a monitor as to view coefficients of lift and drag.

2) At the end of the simulation, open the report>Forces, use x=0, y=1 and vice versa, using your angle of attack and force information it is possible to calculate your lift,drag and coefficients.

Kimican · July 3, 2015, 07:47

First option looks like easier but can i calculate the lift and drag forces by using this option? Actually i can calculate manually this forces after finding coefficients but i want to calculate it with fluent as you know

Thank you

antm324 · July 3, 2015, 10:17

No.1 may be easier to obtain values for one angle of attack as do not forget you will have to change the x and y values to the sin and cos values for the given angle of attack.

if you are running many simulations, different angles of attack i find obtaining the forces in x- and y-direction as the most simple as i can then just load the forces into an excel sheet created that will calculate the lift, drag, Cl and Cd all in one go and saves hours overall!

Kimican · July 4, 2015, 09:16

Thank you dude i got it

Ram97 · April 10, 2018, 01:16

Quote:

Originally Posted by antm324

No.1 may be easier to obtain values for one angle of attack as do not forget you will have to change the x and y values to the sin and cos values for the given angle of attack.

if you are running many simulations, different angles of attack i find obtaining the forces in x- and y-direction as the most simple as i can then just load the forces into an excel sheet created that will calculate the lift, drag, Cl and Cd all in one go and saves hours overall!

Hi. I got my pressure and viscous forces in X and Y direction from the .out file for a 2D airfoil simulation at an angle of attack of 6 deg. I need to manually calculate the lift force. Do you know how to?

fluid23 · April 10, 2018, 17:04

If you have total pressure and viscous forces on the body in X and Y directions, sum each axis and use this:
http://www.aerospaceweb.org/question...cs/q0194.shtml

If you have pressure and shear distributions then you need to use this:
http://web.mit.edu/16.unified/www/FA...ctures/f03.pdf

July 1, 2015, 11:03	Lift and Drag	#1
Kimican New Member Join Date: May 2015 Posts: 28 Rep Power: 10	Hi guys, i want to calculate lift and drag forces and their coefficients for an airfoil.. i will use SST for turbulence model but i do not know how can i calculate lift and drag.. i request your suggestions.. Thank you..

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July 2, 2015, 13:10		#2
antm324 New Member Anthony McCarthy Join Date: Nov 2014 Location: United Kingdom Posts: 21 Rep Power: 11	What Software are you using? If your are using fluent you have ?two? options: 1) You can use the Cl & Cd monitors, under the monitor tab in the solution section, here you can create a monitor as to view coefficients of lift and drag. 2) At the end of the simulation, open the report>Forces, use x=0, y=1 and vice versa, using your angle of attack and force information it is possible to calculate your lift,drag and coefficients.

July 3, 2015, 07:47		#3
Kimican New Member Join Date: May 2015 Posts: 28 Rep Power: 10	First option looks like easier but can i calculate the lift and drag forces by using this option? Actually i can calculate manually this forces after finding coefficients but i want to calculate it with fluent as you know Thank you

July 3, 2015, 10:17		#4
antm324 New Member Anthony McCarthy Join Date: Nov 2014 Location: United Kingdom Posts: 21 Rep Power: 11	No.1 may be easier to obtain values for one angle of attack as do not forget you will have to change the x and y values to the sin and cos values for the given angle of attack. if you are running many simulations, different angles of attack i find obtaining the forces in x- and y-direction as the most simple as i can then just load the forces into an excel sheet created that will calculate the lift, drag, Cl and Cd all in one go and saves hours overall!

July 4, 2015, 09:16		#5
Kimican New Member Join Date: May 2015 Posts: 28 Rep Power: 10	Thank you dude i got it

April 10, 2018, 17:04		#7
fluid23 Senior Member Matt Join Date: Aug 2014 Posts: 947 Rep Power: 17	If you have total pressure and viscous forces on the body in X and Y directions, sum each axis and use this: http://www.aerospaceweb.org/question...cs/q0194.shtml If you have pressure and shear *distributions* then you need to use this: http://web.mit.edu/16.unified/www/FA...ctures/f03.pdf