
[Sponsors] 
August 29, 2005, 05:39 
lift & drag coefficient on airfoil

#1 
Guest
Posts: n/a

dear sirs how can i calculate the lift & drag coefficient on airfoil surface for 2d incompressible case, for fluent post processing i can calculate and draw only cp(pressure coefficient), what about lift & drag coefficient ?? thanks in advance for your early replay


August 29, 2005, 06:26 
Re: lift & drag coefficient on airfoil

#2 
Guest
Posts: n/a

You can monitor lift & drag coefficients while your solution iterates by going to Solve>Monitors>Forces. In fact, if in your final results you want the lift & drag coefficient, then you should monitor them to ensure convergence.
Once you have a final solution you can get forces and moments from Report>Forces. It will print the force (or moment) in your units and in coefficient terms. Make sure you've defined your reference values at Report>Reference values. A sticking point is that "length" is the reference length used in the moment coefficient (Cm = 1/2*Rho*V^2*Aref*Lref) while "depth" is the length of your model in the z direction. If you set "depth" to 1, then it's a per unit length setup. Hope this helps, and good luck, Jason 

October 23, 2009, 01:59 
dear sir..

#3 
New Member
vivit
Join Date: Oct 2009
Posts: 2
Rep Power: 0 
Can you tell me?? What is the Basic Calculation of FLUENT on Computing Lift Coef In Modelling 2D??
thanks 

October 23, 2009, 18:38 

#4 
Senior Member
teguh hady
Join Date: Aug 2009
Location: Surabaya, Indonesia
Posts: 153
Rep Power: 7 
Hy vivit apriliyanti!!
My problem is same as yours!! I think that 2d airfoil don't have A!!! So if A equal to 0 then Cl will be infinite!!! But when we run FLUNT 2D we'll see VOLUME after check our grid!!! the value of volume is not zero!! I think the value of Cl is based on that volume!! hope it helps!! teguhtf 

December 7, 2009, 07:25 
hello mister

#5 
New Member
vivit
Join Date: Oct 2009
Posts: 2
Rep Power: 0 
wahat is grid independensi in FLUENT? please you explain,thnks


December 16, 2009, 08:22 
Basic Computation Of 2D

#6 
Senior Member
teguh hady
Join Date: Aug 2009
Location: Surabaya, Indonesia
Posts: 153
Rep Power: 7 
Sorry, for waiting. After searching in some books, I've opinion that For solving Cl & Cd in 2D. There is assumption that the value of A is 1. you can read this on Anderson Computational Fluid Mechanics And Heat Transfer.
Hope it helps teguhtf
__________________
Now Or Never!!! 

December 16, 2009, 11:14 

#7  
New Member
JT.Q
Join Date: Dec 2009
Posts: 9
Rep Power: 7 
Quote:
2、in force report panal, you can set the force vector to obtain cd and cl respectively.set x=1 and y=0,you will get cd,if x is the velocity direction.set y=1 and x=0, you will get cl. 

December 17, 2009, 09:30 

#8 
New Member
Join Date: Dec 2009
Posts: 3
Rep Power: 7 

March 31, 2015, 19:02 

#9  
New Member
Join Date: Nov 2014
Posts: 8
Rep Power: 2 
Quote:
I am simulating the flow over a 2 element airfoil which is to say that there is a main wing and a flap. I want all coefficients to be scaled to a unit chord. I am unsure whether FLUENT uses the real length of the airfoil or the reference length. I calculate both the lift and drag coefficient on the main, flap and both. However only the main wing and flap combined chord is 1m. I am not quite clear from your explanation what whether FLUENT is assuming a unit chord for all calculations of CL and CD regardless of actual size or if it assumes the actual size. Depth is the z direction or the span of the wing and the length is used for moment how do I define a unit chord? is it in the area value? Thanks in advance for the help. 

Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Lift and Drag Coefficient data for NACA 2412 Airfoil  mahbub03  Main CFD Forum  22  May 25, 2014 15:39 
Lift and drag coefficient with strange values for NACA airfoil  antonio_ing  OpenFOAM Running, Solving & CFD  16  September 13, 2012 12:21 
Fluent Good Lift coefficient BAD drag coefficient  Rif  Main CFD Forum  4  March 9, 2010 11:52 
Automotive test case  vinz  OpenFOAM Running, Solving & CFD  98  October 27, 2008 09:43 
drag and lift coefficient  Noé  CDadapco  5  July 13, 2004 10:21 