Numerical simulation and experiments of multiple reflection and stratified absorption mechanism of pulsed laser in picosecond laser

Based on the combination of computational fluid dynamics (CFD), fluid–solid coupling theory, double-temperature model, C ++ programming and OpenFOAM simulation, this paper investigated the reflection and stratified absorption phenomenon of 10 ps pulsed laser on the surface of materials, calculated the laser reflectivity and stratified absorption coefficient as variables with electron and lattice temperature then innovatively added the calculating module of these variables to the laser processing simulation model. This paper also designed an functional module to simulate the multiple reflection and absorption phenomenon of deep-hole topography to pulsed laser and add it to the simulation model. Furthermore, the energy distribution algorithm in the model which aims at calculating the occupying ratio of energy used in Coulomb explosion and thermal effects has been also modified. The research results combined with experimental verification present that the modified simulation model has a higher accuracy than the original one, which proves that the laser-solid interactions mentioned above have large impacts on the precision of laser processing simulation. It is also proved that the modified energy distribution algorithm is more effective on improving the simulation accuracy than the original one. To sum up, a much more reliable simulation model which has the potential to guide the actual laser processing has been established.