Learning Forum

[nithin.kayarthaya]

Problem

I am trying to simulate the flight of a molten metal  droplet through a gas environment. After the flight, the droplet hits a solid metal surface, spreads on it and solidifies. I want to study the shape of the droplet after solidification 

Approach

The changes in droplet shape are captured using the VOF model and for simulating solidification, Melting/Solidification model is used. The following steps were performed to set up the Melting/Solidification Model.

1. Switch on the Melting/Solidification option in Ansys Fluent
2. Add the additional material properties required
1. For the droplet: Solidus Temperature = 1356K, Liquidus temperature = 1356K, pure solvent heat = 206000 J/kg
2. For the gas environment: Solidus Temperature= 0 K , Liquidus temperature=0K, pure solvent heat = 0 J/kg
3.  During initialization, the droplet region was patched with an initial temperature of 2800K 

Issues

While checking the Liquid fraction contour plots after initializing, the following issues were encountered.

1. The liquid fraction in the gas environment is 1, which should not be the case
2. Wherever the temperature exceeds 1356K (Liquidus of molten metal) in the domain, the Liquid Fraction of molten metal becomes 1. 

It would be really helpful if you could guide me on this issue.

Figure 1  : Domain

Figure  2: Volume fraction of molten copper

Figure  SEQ Figure \* ARABIC 3: Liquid fraction of argon and mixture

Kind regards,
Nithin

[Amine Ben Hadj Ali]

1/Why not? It has to be 1 as you start with higher temperature than liquidus. You ignore that value anyway.
2/Isn't that what it should be: if Temperature is larger than 1356 K you have molten metal and hance liquidus fraction is 1? 

[nithin.kayarthaya]

Dear Dr Amine, 

Thank you for responding.

For point number 1, yes it makes sense that since the liquidus of surrounding gas is given as 0 K, it will always be shown with a liquid fraction 1.

Regarding the second point, 

At t=0 the droplet region is at 2800K and the surrounding gas is at 300K. At this instant liquid fraction of droplet material (liquid copper) = 1 inside the droplet and zero outside the droplet (gas environment)

After some time, when the gas region surrounding the droplet gets heated up above 1356 K (liquidus temperature of copper ) due to the heat transfer, in that region also the liquid fraction of copper turns to be 1 in that gaseous region around the droplet. This does not correspond with the volume fraction results.

 

It would be really helpful if you could share some insights on the same.

 

Thanking you in advance,

 

Kind regards,

Nithin