Today, the laser cutting process is applied in various domains, including in the nuclear industry for dismantling applications. This paper presents the process as it is employed in the context of dismantling thick structures with high precision. The method, although industrialized, remains a rapidly evolving method for nuclear dismantling. A significant challenge concerns the control of laser energy, and more specifically the through-transmitted laser energy, that could affect the background structures. This transmitted laser energy is called “residual laser energy”.

The aim of this communication is to present a multiphysics 3D model of laser cutting process using the finite element software COMSOL Multiphysics®. The model solves heat transfer and fluid flow equations in all states (gas, liquid and solid) and the gas-metal interface is dynamically captured by using the Level Set method. The liquid metal ejection is described and the laser propagation is modeled by ray tracing method, and applied on a dynamic and discrete gas-metal interface through a hybrid Level Set – moving mesh approach, thus allowing for the quantification of residual laser energy.

Experimental observations using two high-speed cameras enable a preliminary validation of the model. The direct cutting front and residual laser energy observations provide a better understanding of physical phenomena occurring during the process. These observations help to determine the cutting front angle, a crucial parameter in this context since it governs the residual laser energy and varies as a function of operating parameters. These angles serve as a basis for comparison with multiphysics simulations.