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lr October 12, 2000 09:37

how to model a free surface
hi; i am a new user of fluent5. I have some problem when i model the free surface of water flowing in a tank that is open to the atmosphere.( boundary condition,velocity distribution) . by the way, how can i give the the shape of surface as it is Thank You in advance!

A.Hassaneen October 14, 2000 06:17

Re: how to model a free surface
I know how to do it in FIDAP but I'm not sure if they are using same idea in Fluent 5. Can anybody advise?

Sung-Eun Kim October 16, 2000 09:51

Re: how to model a free surface
FLUENT 4 and 5 offers a "free-surface capturing" scheme often referred to as Volume-Of-Fraction (VOF) scheme. In this method, FLUENT solves advection equation(s) for a scalar variable (volume fraction) that is a indicator of which fluid a field point is occupied by. The free surface corresponds to the iso-surface where the volume fraction is between 0 and 1 (normally 0.5 is taken).

FLUENT User's Guide has a detailed description of the method, boundary conditions, and some references.

lr October 17, 2000 06:36

Re: how to model a free surface
hi Sung-Eun Kim:

Thank you.

my email is :

I need your help


Shoreh December 6, 2000 15:22

Re: how to model a free surface
As I understand your question is How can you solve a free surface problem by specifying the location of the free surface. In fact you do have the position of the free surface and you are not looking to compute it. All you need to do is to make your mesh in such a manner that the specified free surface shape is in fact one of your boundaries and then give it a symmetry boundary condition in Fluent. If you want to compute the position of the free surface, then you need to use the VOF (which stands for Volume of Fluid) approach of Fluent which is a volume tracking method and will in a very approximate sence compute the position of the free surface. OR you can get Fidap and use the ALE approach of Fidap and compute the shape with a very robust surface tracking algorithm.

lr December 8, 2000 08:51

Re: how to model a free surface
thank Shoreh:

All the problem seems simple to you. and the difficulty is solved in order . Your help is greatly appreciated. best regards.


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