Cd Drag , CdA

caslor · January 20, 2013, 08:16

Hi i would like to ask some theoritical questions

i want to find cd and cda in solidworks

I have an object moving to Z axis in air

i place speed of air - 40m/s

from the type cd = 2Fd / p* V^2 * A

we know :

p = (normal density of air )
v = 40 m/sec

fd = If i place in solidworks at global goals to calculate the normal force in Z axis ... is that the Drag force and so the Fd ??

A = the front aria of my object (cross section area)

Engr.RZA · February 4, 2013, 03:29

Use standard relationship for drag:

Drag Force Coefficient = CD = $\sum$ Fz (in your case) / [1/2 x $\rho$ x V $^{2}$ ]

Here

$\sum$ Fz = Total Drag Force

Boris_M · February 18, 2013, 11:03

Hi caslor,
Normal Force is not the drag force, it is the force normal to the surface only. The normal force is basically the force of the pressure on the surface but not the force due to friction. For drag you should use "Force" and in your case the component of the force in the direction of your flow.

Boris

January 20, 2013, 08:16	Cd Drag , CdA	#1
caslor New Member Join Date: Dec 2009 Posts: 5 Rep Power: 16	Hi i would like to ask some theoritical questions i want to find cd and cda in solidworks I have an object moving to Z axis in air i place speed of air - 40m/s from the type cd = 2Fd / p* V^2 * A we know : p = (normal density of air ) v = 40 m/sec fd = If i place in solidworks at global goals to calculate the normal force in Z axis ... is that the Drag force and so the Fd ?? A = the front aria of my object (cross section area)

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February 4, 2013, 03:29		#2
Engr.RZA New Member RZA Join Date: Nov 2012 Posts: 25 Rep Power: 13	Use standard relationship for drag: Drag Force Coefficient = CD = $\sum$ Fz (in your case) / [1/2 x $\rho$ x V $^{2}$ ] Here $\sum$ Fz = Total Drag Force

February 18, 2013, 11:03		#3
Boris_M Disabled Join Date: Jul 2009 Posts: 616 Rep Power: 23	Hi caslor, Normal Force is not the drag force, it is the force normal to the surface only. The normal force is basically the force of the pressure on the surface but not the force due to friction. For drag you should use "Force" and in your case the component of the force in the direction of your flow. Boris