Title

The nonequilibrium thermodynamics of laser-metal interactions

Date of Completion

January 1992

Keywords

Engineering, Mechanical|Physics, Fluid and Plasma

Degree

Ph.D.

Abstract

Laser drilling of metals and the consequent gas dynamics is investigated. A transient mathematical model is presented for the drilling process which includes: (1) heat conduction and convection; (2) effects of phase change, including vaporization, melting and solidification; and (3) viscous, incompressible flow of melt with a free surface at the melt/vapor interface. The model is evaluated for some two dimensional axisymmetric cases and the results are presented. A transient model for the gas dynamics resulting from the laser induced vaporization in the presence of ambient air is formulated in one dimension. A Knudsen layer analysis is used to model the melt/vapor transition, and flow boundary conditions at the vapor/air interface and at the shock front (when applicable) are included. It was found that the gas dynamics could be modeled by requiring the material derivative of the entropy density to vanish. ^