NUMERICAL TREATMENT OF THE BOUNDARY-CONDITIONS AND SOURCE TERMS ON A SPOT-WELDING PROCESS WITH COMBINING BUOYANCY-MARANGONI-DRIVEN FLOW

Transient heat tranfer, fluid flow, and phase change in spot welding are simulated using a continuum model of total mass, momentum, and energy. Emphasis is given to the numerical treatment of thermal and dynamic boundary conditions and the source terms of the energy equation. The present method for treating the boundary conditions not only can limit the solution domain within the internal control volumes for the overall discretization formulations but also makes it possible to model the free-surface mushy region using the same velocity modification method as in the internal mushy region. In an identical computational environment, the calculated temperature profile, velocity field, and weld pool shape are in excellent agreement with the general iteration method, but the computer speed is faster by 15-20% than that of the latter.