# Displying interface of liquid water using VoF model

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 March 11, 2013, 12:46 Displying interface of liquid water using VoF model #1 Member   Join Date: Aug 2011 Posts: 33 Rep Power: 14 Hello there, I am using a VoF model in FLUENT to model the effect of a gas and wall channel hydrophilicity on the water removal ability. Basically, I have a simple U-turn flow channel, the air goes in at the inlet and exits at the outlet. At the bottom of the channel, a flux of liquid water is applied. After the simulation is converged, some of the liquid water form a liquid film covering the bottom surface of the flow channel. In some cases, there is no liquid film, but some of the liquid accumulates at the corners. Please refer to the pictures attached. pic_1_1.jpg pic_3_1.jpg My question is simple, for a transient simulation, can we not show the animation of a liquid water? a droplet? Is it the same as defining an ISO-surface of volume fraction of liquid water and then record it at each time step when the simulation progresses? Regarding the ISO-surface of the volume fraction of liquid water, what should be the value of interest? Which value represent the water droplet interface? Is it 0.1? or 1? I have seen somebody mention a 0.5 would be what I want, can someone confirm this please? Best regards, Pattarapong

 March 11, 2013, 14:29 #2 Senior Member   OJ Join Date: Apr 2012 Location: United Kindom Posts: 473 Rep Power: 19 Yes, you need to save the VF of water at every step to be able to have any animation. Regarding free surface, how about this... Plot a graph of VF versus height from bottom of the channel to top. You will see the VF of water going from 1 to 0 (Or values close to 0) over a transition distance. This is your layer of free surface, transitioning from water to air. Focus on this transition layer and spot the VF of water exactly in the middle. Use this VF to generate isosurface. Workable, unless someone has better idea OJ pchoopanya likes this.

 March 15, 2013, 17:42 #3 Member   Join Date: Aug 2011 Posts: 33 Rep Power: 14 Thank you very much for your valuable comment, i'll try this !