If we can understand these phenomena, we can assist process optimization. It is important to track the locations of interfaces because the transport properties of solid, liquid, and vapor phases differ greatly. If we know the interface locations, we can assign the appropriate modeling equations to specific phases. The effects of viscosity, for example, are included in the liquid phase but not in the solid phase. Mesh points are kept on the interface as it moves.
Interior points remain smoothly distributed within a material phase.
At each iteration, or time step, robust implicit methods are used to calculate grid-point locations simultaneously with field variables such as velocity and temperature. We use the MELT program to model the material and energy flow in an electron-beam vaporizer for aluminum. A portion of the beam energy is used to vaporize the aluminum. Another fraction is lost to thermal radiation and the formation of secondary electrons. The balance is transported by convection and conduction to the crucible.