a big problem when using VOF + melting/solidification model
 

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.
Attachment 54618

after 0.02s
Attachment 54619

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?

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?

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?

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.

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.

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

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.