Modeling keyhole phenomena self-consistently and efficiently yet remains a major challenge. A unique approach involving heat transfer, fluid mechanics, phase transformation physics as well as tracking of the liquid/vapor interface is adopted in the present study. Computation has been carried out in three dimensions. A mathematical scheme called the fast level set technique has been utilized to capture the transient L/V interface. Inherent to this technique are: the ability to simulate merger and splitting of the L/V interface, and simultaneous updating of the surface normal and the curvature. The kinetic Knudsen layer has been considered to simulate evaporation phenomena and recoil pressure. Thermocapillary force and the recoil pressure have been coupled with the flow simulation. Energy distribution inside the keyhole is computed considering the multiple reflection phenomena. The effect of laser power on the surface temperature and keyhole shape is presented and discussed. The theoretical predictions are compared with experimental observations.

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