How the force derived on a 2D model?

rikio · October 10, 2010, 06:13

As we all know, force is the integral on a wall surface, that means, surface area must not be zero. But my question is, how the force derived on a 2D model which has no area.
For example, the problem of a cylinder in a fluid field. The 2D model in FLUENT is only a circle, the force could be reported that to tell you how much Newton of drag force on the circle is. How this be derived?
Is there any clue in the HELP document?

Thanks in advance.

rikio · October 10, 2010, 06:28

I used to think that the force is based on the existing 2 dimensions of the 2D model and one unit in the other dimension. If the model is built in mm, the third dimension is 1mm. And if in m, it is 1m.

But a model of a 1000mm x 50mm in a 20m/s wind field gets a relatively big drag force, that makes me doubting the derivation.

rikio · October 11, 2010, 22:41

Problem solved.

October 10, 2010, 06:13	How the force derived on a 2D model?	#1
rikio Senior Member Rikio Join Date: Mar 2009 Location: SH, China Posts: 182 Blog Entries: 1 Rep Power: 17	As we all know, force is the integral on a wall surface, that means, surface area must not be zero. But my question is, how the force derived on a 2D model which has no area. For example, the problem of a cylinder in a fluid field. The 2D model in FLUENT is only a circle, the force could be reported that to tell you how much Newton of drag force on the circle is. How this be derived? Is there any clue in the HELP document? Thanks in advance.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
How to include lift forces/wall lubrication forces in the MIXTURE multiphase model?	hohomm	FLUENT	0	December 17, 2009 06:45
DEFINE_CG_MOTION and pressure force	Teo Fumagalli	FLUENT	0	April 11, 2008 11:25
Kato-Launder model	sam	Main CFD Forum	13	September 21, 2006 11:15
DPM model w/ Wave model - errors in documentation	HS	FLUENT	0	April 12, 2006 05:37
drag force in two phase flow	Ken	CFX	5	November 21, 2005 16:28

October 10, 2010, 06:28		#2
rikio Senior Member Rikio Join Date: Mar 2009 Location: SH, China Posts: 182 Blog Entries: 1 Rep Power: 17	I used to think that the force is based on the existing 2 dimensions of the 2D model and one unit in the other dimension. If the model is built in mm, the third dimension is 1mm. And if in m, it is 1m. But a model of a 1000mm x 50mm in a 20m/s wind field gets a relatively big drag force, that makes me doubting the derivation.

October 11, 2010, 22:41		#3
rikio Senior Member Rikio Join Date: Mar 2009 Location: SH, China Posts: 182 Blog Entries: 1 Rep Power: 17	Problem solved.