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

#1 
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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

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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

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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 
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alessio
Join Date: Nov 2009
Posts: 5
Rep Power: 7 
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 

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Quote:


August 27, 2011, 20:32 

#6 
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Tobino
Join Date: Jan 2011
Location: Osaka,Japan
Posts: 33
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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 
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March 18, 2014, 02:07 
Calculating forces

#8 
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Aalisha
Join Date: Jan 2014
Posts: 18
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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 
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Jakub
Join Date: Feb 2014
Posts: 4
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