What is the flow rate through a capillary tube?

[ratzmoose]

Hi,

I was wondering if there was an equation for the flow rate through a straight vertical or angled capillary tube. All I can find is how to calculate the height it rises but I would like to know how to find the rate it rises. I imagine it is not a steady rate since it must stop once it reaches it's max height however just to be able to get the time it would take to get to that point should suffice for what I am doing.

Any help would be greatly appreciated.

Thanks

 

[Chestermiller]

Check out the Hagen Poiseuille equation. This equation would have to be modified to include hydrostatic pressure effects.

Chet

 

[Andy Resnick]

It's a surprisingly tricky problem:

http://ocw.mit.edu/courses/mathemat...-2010/lecture-notes/MIT18_357F10_Lecture8.pdf