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# Drag Coefficient for a Hollow Cylinder

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## Drag Coefficient for a Hollow Cylinder

(OP)
Can anyone tell me the drag coefficient for a hollow cylinder through a fluid?

The fluid in question is viscous (50+ cP for the purposes of calculations) and incompressible with a density of 1800 kg/m^3.  The cylinder is 30.5cm long with an inner diameter of 7cm and outer diameter of 8.9cm.  Velocity is in the range of 14 to 15 m/s.

I'm afraid my rather basic fluid mechanics text, just doesn't have info on a hollow cylinder.

### RE: Drag Coefficient for a Hollow Cylinder

(OP)
Whoops!  Forgot to mention the cylider is moving through the fluid parallel to its long axis.

That is to say that the fluid is flowing through the hollow portion and around the outer diameter.

### RE: Drag Coefficient for a Hollow Cylinder

(OP)
Thanks, Greg.  I'll give that a try and see how it turns out.

### RE: Drag Coefficient for a Hollow Cylinder

Depending on how accurate you need your analysis to be this could be reasonably approximated by a flat plate with the width of the plate being the circumfrence of the tube.

Kirby Wilkerson

Remember, first define the problem, then solve it.

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