A continuum mixture model for moving pulsed laser phase change process

A two-dimensional, transient model is proposed to investigate the effect of scanning speed and Marangoni convection on the prediction of depth and width of the melt pool in a laser melting process. The laser beam is moving over the work piece surface and repetitive in nature. One-phase continuum mixture theory has been explored to develop this model. The laser beam is assumed to follow spatial Gaussian and transient trapezoidal distribution. The laser pulse is irradiated on the Titanium surface. To simulate in line with the experiment, the laser source is taken as a volumetric heat source. Natural convection is considered in the melt pool. Radiation and convection heat losses from the irradiated surface are taken into account. The finite volume method is used to discretize the governing equations of mass, momentum and energy. The SIMPLER algorithm is adopted to solve the flow field in the melt pool. The enthalpy-porosity approach is used to capture the solid-liquid interface while phase change proceeds. The temperature predicted using this proposed model is validated against the available experimental results and a good agreement is found. Finally, it is found that the scanning speed and Marangoni convection play an important role in predicting the shape and size of the melt pool.