a big problem when using VOF + melting/solidification model

pancard · March 13, 2017, 13:04

hi, friends, i try to simulate the welding process using VOF + melting/solidification models in FLUENT. it is a simple principle that metal is solid and won't move below solidus temperature.
However, i found the situation was not like that.
let's look a simple test case.
this is initial state; constant ambient temperature; the whole region is considered as fluid domain. of course the melting/solidification model is used.
001.png

after 0.02s
002.png

metal material is apparently moving, which is wrong.

any one have a idea about what is going on here? is it because the solid is a fake solid in VOF model?

LuckyTran · March 13, 2017, 23:44

Okay the pics aren't labeled or anything but I'm guessing that blue/red is solid/liquid phases or vice-versa. The phase boundary should move in a melting/solidification problem. How are you sure the stationary solid has been moved versus motion of the phase boundary?

pancard · March 14, 2017, 09:30

yes, the red is metal at solid temperature, the blue is air
comparing the tow figures, the interface shape apparently changed.

LuckyTran · March 14, 2017, 11:18

Quote:

Originally Posted by pancard

yes, the red is metal at solid temperature, the blue is air
comparing the tow figures, the interface shape apparently changed.

Yes, the "interface" is the phase boundary. If there is melting/solidification then the phase boundary moves as the amount of solid increases/decreases. Is that not what is happening here?

pancard · March 14, 2017, 11:25

Quote:

Originally Posted by LuckyTran

Yes, the "interface" is the phase boundary. If there is melting/solidification then the phase boundary moves as the amount of solid increases/decreases. Is that not what is happening here?

Actually, the metal is titanium, the temperature remains constant at 300K. No melting is happening. so the interface is not supposed to change, because it is solid/gas interface in reality.

pancard · March 16, 2017, 10:03

i think i've figure out the reason. it is due to surface tension. I forgot set zero value of surface tension when temperature drop to below solidus point.
I'm running a test case to prove this hypothesis.

Hossein95 · May 18, 2020, 16:31

Hi Pancard
I have same problem as you, did you find the solution?
If you have foun that, help me please

Amit@455 · April 29, 2024, 14:25

Hi Hossein/Pancard
Facing the same issue.. my solid metal is deforming even before the it reached solidus temperature. Please help.
I have tried by taking surface tension as zero below solidus and 1.0 above liquidus temperature still the problem is not solved.

March 13, 2017, 13:04	a big problem when using VOF + melting/solidification model	#1
pancard New Member Join Date: May 2012 Posts: 5 Rep Power: 14	hi, friends, i try to simulate the welding process using VOF + melting/solidification models in FLUENT. it is a simple principle that metal is solid and won't move below solidus temperature. However, i found the situation was not like that. let's look a simple test case. this is initial state; constant ambient temperature; the whole region is considered as fluid domain. of course the melting/solidification model is used. 001.png after 0.02s 002.png metal material is apparently moving, which is wrong. any one have a idea about what is going on here? is it because the solid is a fake solid in VOF model?

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March 13, 2017, 23:44		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,676 Rep Power: 66	Okay the pics aren't labeled or anything but I'm guessing that blue/red is solid/liquid phases or vice-versa. The phase boundary should move in a melting/solidification problem. How are you sure the stationary solid has been moved versus motion of the phase boundary?

March 14, 2017, 09:30		#3
pancard New Member Join Date: May 2012 Posts: 5 Rep Power: 14	yes, the red is metal at solid temperature, the blue is air comparing the tow figures, the interface shape apparently changed.

March 16, 2017, 10:03		#6
pancard New Member Join Date: May 2012 Posts: 5 Rep Power: 14	i think i've figure out the reason. it is due to surface tension. I forgot set zero value of surface tension when temperature drop to below solidus point. I'm running a test case to prove this hypothesis.

May 18, 2020, 16:31		#7
Hossein95 New Member Hossein Join Date: May 2020 Posts: 1 Rep Power: 0	Hi Pancard I have same problem as you, did you find the solution? If you have foun that, help me please

April 29, 2024, 14:25		#8
Amit@455 New Member Join Date: Aug 2021 Posts: 1 Rep Power: 0	Hi Hossein/Pancard Facing the same issue.. my solid metal is deforming even before the it reached solidus temperature. Please help. I have tried by taking surface tension as zero below solidus and 1.0 above liquidus temperature still the problem is not solved.