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Elliot Schwartz August 11, 1998 08:46

Modeling Free Surface Flows
Does anyone know of any journal articles or survey papers addressing the topic of CFD modeling of free surface flows? I am interested in the use of commercial codes and any comparisons of their performance and accuracy under various conditions, but any references on free surface flows would be useful. In particular, I am interested in low-Reynolds number free surface flows, but again, any references on CFD analysis of free surface flows would be useful.

Thanks in advance for any help and thanks to Jonas Larsson for providing this forum.

Elliot Schwartz

Jonas Larsson August 11, 1998 09:54

Re: Modeling Free Surface Flows
Flow Science Inc. has a lot of info on free-surface simulations available online. You can find their homepage at:

However, this is a commercial site and you won't get a very objective picture I'm afraid, but it's better than nothing. Btw, I'm glad you like this forum.

Philip Zwart August 11, 1998 10:19

Re: Modeling Free Surface Flows
There are several different approaches to modelling free surface flows, and more than one way to classify them. I like the terminology "interface-tracking" and "interface-capturing". The following paper describes methods in both categories:

@InCollection{MuzPer98, author = {S. Muzaferija and M. Peri\'{c}}, title = {Computation of free-surface flows using interface-tracking

and interface-capturing methods}, booktitle = {Nonlinear Water Wave Interaction}, editor = {O. Mahrenholtz and M Markiewicz}, publisher = {Computational Mechanics Publications}, year = 1998 }

and it also has references to earlier fundamental papers.

Interface-tracking means the computational mesh adapts the the free surface at all times. This works well provided the boundary motion is not too complex. For my Ph.D., I'm developing a method of this type for 2d flows which works for (fairly) arbitrary motions provided there is no colliding of interfaces.

Interface-capturing means the surface is captured by solving auxiliary equations (such as the fluid volume) over a domain which encompasses the interface. These methods are more general in that they can handle colliding interfaces. But a lot of things need to be done right in order to get a sharp interface. The Flow Science web page which Jonas mentioned has some impressive pictures of complex motions.

Hope this helps,


R Sukumar August 11, 1998 12:22

Re: Modeling Free Surface Flows
CFD-ACE+ from CFD Research Corporation has a VOF free surface capability. Some preliminary information focussed on plastic encapsulation of electronic components is available on Plastic Encapsulation.

More comprehensive information will be published soon.

R. Sukumar CFD Research Corporation

Elliot Schwartz August 13, 1998 08:39

Re: Modeling Free Surface Flows
Thanks to Jonas, Philip, and Mr. Sukumar for your quick responses. They provided much useful information.

Elliot Schwartz

Sung-Eun Kim August 25, 1998 21:03

Re: Modeling Free Surface Flows
We've been employing the so-called "volume-Of-Fluid" method in our software (FLUENT 4.4 and FLUENT 5.0) which is a fixed grid method (structured and unstructured mesh)for tracking free surface. And in Fidap, one of our CFD products, we have employed a Arbitrary Lagrangian-Eulerian (ALE) based free-surface tracking scheme.

The two approaches (fixed grid and ALE) have advantages and disadvantages. For free surface with large deformation (e.g. wave-breaking, liquid sloshing in tanks), the fixed grid method might be the choice, for instance.

I hope you don't think I'm making a sales pitch.

Good Luck, Sung-Eun

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