
[Sponsors] 
March 11, 2000, 09:45 
Calculating drag coefficient from Fluent

#1 
Guest
Posts: n/a

Can any one tell me how to calculate drag coefficient from Fluent on the 2D airfoil. I have done this using wall force(from fluent display) taking Xdirection normalforce + xdirection shear force divide by 0.5u*2 but i end up getting the wrong result. Could any one tell me if this is the right approach.


March 28, 2000, 10:16 
Re: Calculating drag coefficient from Fluent

#2 
Guest
Posts: n/a

Solve / Monitor / Surface / Drag Then chose the airfoil edges to compute the drag force from.
To get a nondimensional drag coefficient, set your airfoil parameters in the following section : Report / Reference values Set length, speed, rho etc. The reported Cd should be ok now. Good luck. Cheers, Flav 

March 30, 2000, 00:24 
Re: Calculating drag coefficient from Fluent

#3 
Guest
Posts: n/a

Hi Richard,
I also tried to plot the Cd profile for flow past a circular cylider case but the results are not coming correctly. I followed this way. Solve/Monitors/Force/Drag ... then I chosen the curve for Cd plot. I set the density, velocity, but not the length at Report / Reference values. I wonder whether length details are truly needed for calculating the Cd value. Bye, Jalaiah 

February 15, 2010, 10:12 

#4 
New Member
alessio
Join Date: Nov 2009
Posts: 5
Rep Power: 8 
Hi guys, i'm tring to calculate the drag force coefficient in a 3d case and the fluid is behind a cylinder.
the fluid is: density = 800 kg/m^3 dinamic viscosity = 0.005 kg/ms velocity = 8 m/s the cylinder is: diameter = 13 mm length = 300 mm stiffness modulus = 200000 MPa poisson coefficient = 0.3 to calculate the drag coefficient i push: solve/monitors/force/drag coefficient..... the direction of the vector of force is in parallel to the flow flowing i set the reference value: Area = 0.013*0.3 that is the product for diameter and the length of the cylinder, Length = 0.013 that is the diameter then i set other values: viscosity, velocity, density of fluid as i wrote upforward. i put 90 nodes around the circonference of the cylinder, and 25 along to the length of the cylinder. the algorytm used is LES, because this is a 3d case I used PISO and second order upwind for momentum... the Cd value is incresing but after 0.02 seconds it is still to 0.7. How can i do, please help me. Alessio Thank to all 

July 7, 2011, 05:53 

#5  
Member

Quote:


August 27, 2011, 20:32 

#6 
Member
Tobino
Join Date: Jan 2011
Location: Osaka,Japan
Posts: 33
Rep Power: 6 
Hi,
I am using Fluent to calculated Force too, my model is a hull of ship. my results showed that the Viscous Force is ok but the Pressure Fore is not corrected. Anybody knows what is wrong? Tobino, 

September 20, 2011, 09:11 

#7 
Member


March 18, 2014, 02:07 
Calculating forces

#8 
New Member
Aalisha
Join Date: Jan 2014
Posts: 18
Rep Power: 3 
Hello, I have created a 3D model of a 3 blade tidal current turbine with the blade length 710 mm and blade width 162 mm. It is surrounded by a cylinder which will act as a rotor and finally by a brick acting as a stator.
After exporting the mesh from gambit 2.2.30 to fluent 6.1, I want to calculate the drag and lift force on the walls of the blades. I have defined the units (angular velocity into rpm), grid interfaces, boundary conditions. However when I follow the command Solve>> Monitors>> Forces It shows an error saying " No data to plot". If anyone can explain this? 

February 17, 2015, 08:45 

#9 
New Member
Jakub
Join Date: Feb 2014
Posts: 4
Rep Power: 3 

September 21, 2015, 03:24 

#10 
New Member
N B Khan
Join Date: Jan 2014
Posts: 24
Rep Power: 3 

September 21, 2015, 04:44 
yeap

#11 
Member

It depends on what are you looking for?!
If you are looking for Cd, based on results obtained for aerdynamic force,then these results might not be correct if reference are is not correct.
__________________
I'M NOT A GYNECOLOGIST BUT I'LL TAKE A LOOK. 

Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
a problem in drag coefficient calculating  anijdon  OpenFOAM  1  March 20, 2013 13:11 
Incorrect Drag and Drag Coefficient for flow over a cylinder  ozzythewise  Main CFD Forum  8  June 13, 2012 06:24 
Reference Area for Calculating Lift and Drag Coefficient of 3D wing  mahbub03  Main CFD Forum  3  May 19, 2011 00:21 
Drag coefficient for parcels in dieselFoam  sebastian_vogl  OpenFOAM Running, Solving & CFD  5  December 31, 2008 13:19 
drag coefficient  Jean  FLUENT  14  November 4, 2002 04:49 