NUMERICAL ANALYSIS OF ULTRAFAST HEAT TRANSFER WITH PHASE CHANGE IN A MATERIAL IRRADIATED BY AN ULTRASHORT PULSED LASER

Abstract

This study is concerned with problems of ultrafast and high heat flux heat transfer with phase change. We employ the cubic interpolated propagation (CIP) method coupled with a thermoconvective model to examine the history of large-scale phase change, that is, melting and evaporation, and the mechanisms of heat transfer as a wave. It is found that wave-type heat transfer as a shock wave with phase change can be simulated without a hyperbolic heat conduction equation by means of the CIP method. Melting and evaporation occur in the energy deposition region, and energy is transferred by a shock wave beyond an energy penetration depth. The propagation velocity is hardly damped outside the energy deposition region inside aluminum thin foil, but the peak value in density, pressure, and temperature is damped rapidly. For one of the dissipation process mechanisms, generation of thermal stress can be considered. Further, it is found that the initial velocity of shock wave generated inside the energy deposition region is different for each initial incident laser intensities, though the propagation velocity is constant beyond the energy penetration depth in spite of an initial incident laser intensity.