[fangdian]

Hi,
I want to simulate the welding pool(which comes from the molten steel for the heating of welding arc to the melting steel plate) in the arc welding, taking the natural-convection flows in the welding pool.
I use the VOF and solidfication & melting model in my case and I want to consider the buoyancy with the Boussinesq model in the fluent as follws:

In my case, there are two phase which are the ideal air(primary phase) and the steel(second phase). I have set the solidus temperature as 1773K and the liquidus temperature as 1793K. The density of the steel and ideal air are 7860kg/m3 and 1.225kg/m3. The thermal expansion coefficient of steel is 1e-4.
With respect to my case, how to set the parameters for the Boussinesq model? I can set the density of the flow with the density of primary phase, that is to say,the density of the ideal air 1.225kg/m3. But how can i set the is the operating temperature, the solidus temperature or the liquidus temperature of the steel plate(the second phase) in the expression above?
Thanks.