Air and Water VOF model, Error??

July 18, 2002, 02:53

I am simulating an empty tank filled with water (water inlet is at bottom of the tank, air outlet at top) using a VOF model. Although I turned on the gravity and body force options, the results show that the air and water are mixed together rather having a clear interface with water at the bottom and air at the top. Who can tell me what's the problem? Thank you in advance.

July 18, 2002, 06:04

What type of VOF you are using ? Fluent offers 4 type, right ?? DC

July 18, 2002, 22:14

Thank you. There are three types of discretization schemes for Volume of Fluid (VOF) offered by Fluent. I tried Implicit and Geo-Restruct. The problem persists. Looking forward for your advise.

July 18, 2002, 23:45

Use Geo-Restruct and also use VOF under relaxation 0.5. Try to use gradient of VOF after few time steps. You should be fine.

DC

July 19, 2002, 00:00

Thank you for your quick reply. For Fluent 6.0, there is no under relaxation factor with Geo-Restruct. What do you mean by "gradient of VOF". Looking forward for your reply.

July 19, 2002, 04:08

Try to adapt the grid based on the gradient of volume fraction of one phase.

July 18, 2002, 02:53	Air and Water VOF model, Error??	#1
boris Guest Posts: n/a	I am simulating an empty tank filled with water (water inlet is at bottom of the tank, air outlet at top) using a VOF model. Although I turned on the gravity and body force options, the results show that the air and water are mixed together rather having a clear interface with water at the bottom and air at the top. Who can tell me what's the problem? Thank you in advance.

July 18, 2002, 06:04	Re: Air and Water VOF model, Error??	#2
david Guest Posts: n/a	What type of VOF you are using ? Fluent offers 4 type, right ?? DC

July 18, 2002, 22:14	Re: Air and Water VOF model, Error??	#3
Boris Guest Posts: n/a	Thank you. There are three types of discretization schemes for Volume of Fluid (VOF) offered by Fluent. I tried Implicit and Geo-Restruct. The problem persists. Looking forward for your advise.

July 18, 2002, 23:45	Re: Air and Water VOF model, Error??	#4
david Guest Posts: n/a	Use Geo-Restruct and also use VOF under relaxation 0.5. Try to use gradient of VOF after few time steps. You should be fine. DC

July 19, 2002, 00:00	Re: Air and Water VOF model, Error??	#5
Boris Guest Posts: n/a	Thank you for your quick reply. For Fluent 6.0, there is no under relaxation factor with Geo-Restruct. What do you mean by "gradient of VOF". Looking forward for your reply.

July 19, 2002, 04:08	Re: Air and Water VOF model, Error??	#6
david Guest Posts: n/a	Try to adapt the grid based on the gradient of volume fraction of one phase.

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