- #1

thepopasmurf

- 76

- 0

I was looking through some of my old notes and I had an equation for the capillary force:

f

_{c}= γ cosθ dS/dx

where γ is the surface tension,

θ is the contact angle,

S is the surface area to be covered by the liquid (not the cross-sectional surface area, A)

x is the direction of motion of the liquid.

With this equation, I can correctly deduce the capillary pressure in a cylinder (2γ cosθ / r),

and between parallel plates (2γ cosθ / h).

Can this equation be applied to an arbitrary (constant) cross-section?

Usually I see this kind of question tackled with the Young-Laplace equation, but that seems to be complicated for arbitrary cross-sections.