If there is a weld pool solver that computes the weld pool free surface, velocity and temperature in the weld pool and weld pool reinforcement, the input data should include the thermal flux, mass flux, current density distribution from the arc and pressure distribution from the arc. The viscosity of the liquid and density of the liquid will be required input data.

If the liquid-solid interface is interpreted as a sharp interface and not a mushy zone, then the jump condition across the interface is the Stefan condition:

[q]^qs-<h=Lv-n (9-1)

where qs is the thermal flux on the solid side of the interface, ql is the

thermal flux on the liquid side of the interface, L is the latent heat of fusion, v is the velocity vector and n is the outward normal oriented from solid to liquid.

The Stefan jump condition implies that the thermal gradient in the front half of the weld pool will be negative.

The melting temperature will be raised on melting and lowered on solidification by the velocity due to kinetics effects.

The melting point will also be depressed by curvature for a solid sphere.