FINITE-ELEMENT ANALYSIS OF FLOW, HEAT-TRANSFER, AND FREE INTERFACES IN AN ELECTRON-BEAM VAPORIZATION SYSTEM FOR METALS

A numerical analysis is made of the liquid flow and energy transport i n a system to evaporate metals. The energy from an electron-beam heats an axisymmetric metal disk supported by a water-cooled platform. Meta l evaporates from the surface of a hot pool of liquid which is surroun ded by a shell of its own solid. Flow in the pool is strongly driven b y temperature-induced buoyancy and capillary forces, and is located in the transition region between laminar and turbulent flow. The evapora tion rate is strongly influenced by the locations of the free boundari es. A modified finite element method is used to calculate the steady s tate flow and temperature fields coupled with the interface locations. The mesh is structured with spines that stretch and pivot as the inte rfaces move. The discretized equations are arranged in an 'arrow' matr ix and are solved using the Newton-Raphson method. The electron-beam p ower and platform contact resistance are varied for cases involving th e evaporation of aluminum. The results reveal the interaction of liqui d flow, heat transfer and free interfaces. (C) 1998 John Wiley & Sons, Ltd.