Ask an elementary question:

What's VOF? Can any friend give a brief discription? Thanks a lot.

wen

I think it is some kind of method for multiphase flows...try to do a Google or yahoo query "VOF CFD"

VOF: Volume of Fluid.

When one wants to solve a multiphase flow problem say an air bubble rising in water he has a choice how to solve it.

1) solve the NS eqn in the water phase, solve the

NS eqn in the air phase and then see if the

boundary conditions are satisfied. if not

attempt a correction and try again. iterate

until patience has run out.

2) Use a one-fluid formulation which reduces (or masks)

the NS eqn into one equation and the correct eqn is

found via an indicator function (or step function).

Ie. we are in the water phase if indicator function

is one and zero if indicator function is zero or

on the boundary if indicator function is undefined.

(much easier to impliment into existing codes)

Now, VOF is a technique which is used to capture

or follow this indicator function via the scalar

advection equation.

CAUTIONARY WARNING FOR 3-D:

Not for people who failed geometry class!!!

better yet just goto the search on this site and search VOF in the general forum... There will be alot of links.

See Hirt and Nichols "Voulme of Fluid VOF method for the dynamics of free boundaries", J. Comp. Phys. 39, 201-225, 1981.

If you do a search in the cfd-online forum, you will be able to get lots of discussions about VOF.