Abstract: Abstract:Materials were cut with the coupled interaction of laser power and assistant gas during laser cutting process.A multiphase flow model was established,which was able to reflect the interaction among laser energy,assistant gas and workpiece during laser cutting based on computational fluid dynamics.A hybrid heat source model was used,including laser power and oxygen-flow controlled combustion reaction heat.Low carbon steels were cut by fiber laser with O₂ or N₂ as assistant gas,and the cutting process was numerically simulated.The effect of laser power and assistant gas on laser cutting ability was investigated by regulating the laser power and gas pressure.The calculated results show that the laser cutting ability was determined by the coupled interaction of laser power and assistant gas.The numerical simulation can calculate both the temperature and flow fields, and can also predict the shape of cutting seam.