Multi-physics simulation of complex flow and phase change induced by a localized laser irradiation on a urethane-coated stainless steel substrate

A three-dimensional numerical simulation is conducted for a complex process in a multicomponent-multiphase system, which involves heat and mass transfer in the compressible gaseous phase and chemical reaction during laser irradiation on a urethane paint coated on a stainless steel substrate. A finite volume method (FVM) with a co-located grid mesh that discretizes the entire computational domain is employed to simulate the laser irradiation process. The entire problem is solved within one computational domain that includes two solid regions and one fluid region. To be specific, for the considered solid region, the paint will be decomposed via chemical reaction to gaseous phases then mix into the air and the stainless will involve phase change phenomena, such as melting-solidification and vaporization-condensation, once melting or boiling point is reached. Moreover, the air region is considered as a multicomponent phase that has O₂, N₂, CO₂, H₂O, NO₂, binder vapor and stainless vapor. In this multi-physics simulation, the process of melting, vaporization and chemical reaction and the splash of the melted paint and stainless into the air is observed. In the following sections, details on physical models will be given for each key component of the strategy in solving the entire problem. And the last section will show the results and corresponding discussion. This work is done within the framework of the OpenCFD toolbox OpenFOAM [1].