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Marco September 24, 2001 06:29

Free interfaces
Has someone experience of drop impact simulations with CFx? In which conditions ? Is it really working ? Thank you for helping me to decide to use CFx or not...

Astrid September 24, 2001 15:58

Re: Free interfaces
What do you exactly mean by 'drop impact'. Rain drops falling on a liquid surface? Please be more specific.

Marco September 25, 2001 05:43

Re: Free interfaces
Yes, for example, raindrop impact on shallow water. But it could be a drop impacting on a dry aluminium plate. I need information on the deformation evolution, lamella spreading and so on. I know that it is a difficult problem, but this is just what I would like to test using a commercial code: validating its ability to simulate this complex process. Thank you for any help.

John C. Chien September 25, 2001 12:15

Re: Free interfaces
(1). You can get free demo and nearly free (very cheap, for $30.US?) code at : "New version of NS solver available at

or get install file quickly at:

best regards for all fld developers,

maq" This was posted in the main discussion forum recently. (2). It has a free falling water drop impacting on a surface.

Michael Rasmussen September 26, 2001 11:42

Re: Free interfaces
I think John is right

You need a true VOF model for your problem. However I think that the (very impressive looking) model suggested by John is presently a 2D model - and your particles are 3D. If you buy the source code you can expand it yourself (if you have the time and energy). I would also suggest that you look at the Flow3D model


a company founded by Dr. Hirt - the pioneer within VOF.

Which gives me the chance to ask the obvious question in this CFX forum : WHEN does AEA release a CFX4 version with true VOF ? - COME ON FRIENDS WE NEED IT !!

Understand me right : The moving grid is great, but it cannot solve separation of fluid particles into air.

Best Regards Michael

Chucky Bob September 26, 2001 13:42

Re: Free interfaces
I don't think CFX can handle large density and surface tension ratio's (ie. air water). I think we got up to 50 or 100 and the code just died.

there is a thesis by Denis Gueyffier Universite Pierre et Marie Curie.

Search "Zaleski" "lmm" on it will take you to the professors web page. You can download the thesis that deals with impacting drops and the code that was used.

Sascha September 27, 2001 06:27

Re: Free interfaces
cfx-4 is not able to deal with drop impact on surfaces. Here it is the best to use FLOW-3D. It is the best code on the market for VOF. CFX-4 is only good when you want to deal with the TWO-FLUID-model and the interactions between the two fluids but not for free surfaces.

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