# Could Anyone guide me about drag force

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 September 19, 2009, 00:56 Could Anyone guide me about drag force #1 New Member   Attapon Join Date: Sep 2009 Posts: 2 Rep Power: 0 Hello I'm ACJ. I'm a newbie in CFD and ofcourse in this forum also. Now I'm trying to use cfx to find Drag force/Drag coefficient of flow pass though the cylinder. I set up model in DesignGeometry , define BCs, build a mesh and then solve it. The result is shown by pressure, velocity etc. I try to find there are option in cfx that can show drag-force result like cosmosflowork can do. Could anyone guide me how to find drag force or other (lift, momnet) by cfx ? Thank in advance sincerely your ACJ

 September 19, 2009, 21:11 #2 New Member   kumar Join Date: Sep 2009 Posts: 4 Rep Power: 9 Hi In CFX you need to create expressions to get drag force. CFX will give you forces in x and y directions like force_x & force_y.using this forces you can find normal force(cn) & tangential forces(ct).Based on angle of attack ,now you can find drag force with the formula Cn*sin(aoa)+Ct*cos(aoa);

 September 21, 2009, 15:06 #3 New Member   Join Date: Aug 2009 Posts: 13 Rep Power: 9 In CFX post, go to calculator and then find force in the y direction at the cylinder

September 29, 2009, 02:46
LIFT and DRAG calculation in CFX, plotting Cd and Cl
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sharanappa
Join Date: Apr 2009
Location: INDIA (BHARAT)
Posts: 8
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Quote:
 Originally Posted by cfd_lean Hi In CFX you need to create expressions to get drag force. CFX will give you forces in x and y directions like force_x & force_y.using this forces you can find normal force(cn) & tangential forces(ct).Based on angle of attack ,now you can find drag force with the formula Cn*sin(aoa)+Ct*cos(aoa);
I am new to using CFX. I am doing analysis of flow over a rotor wing with two blades, the geometry is little complex. I have considered a cylindrical domain around the rotor and done the analysis. In the force and torque monitors am getting the values of forces and torque on the rotor and domain separately. I want to find out the Lift and Drag (rotor is at zero angle of attack, lift may be small value) and the power required to drive the rotor at that particular rpm (this am calculating manually by taking the tangential torque value).

I have a doubt : in the monitors there are two options Normal moment and tangential moment. I have considered tangential moment for calculation of power as that value is higher.

I also want to plot the Cl and Cd graphs.

Can you please elobrate how to write expressions to calculate lift and drag and also to plot Cl and Cd.

let me know if there is a tutorial for these things.

thanks

sharantillu@gmail.com

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