Influence of Surface Geometry on Melt Pool Flows and Shape in Pulsed Laser Surface Melting

Pulsed Laser Surface Melting (pLSM) is a technique that offers an efficient way to modify the geometry surfaces without any addition or removal of material. In pLSM, an incident laser beam melts a small region on the surface and induces surface tension and viscosity-driven flows that modify the surface geometry. Initial surface geometry plays an important role in deciding the melt pool flows and shape as it governs the initial surface tension acting on the melt pool. In this paper, we present a systematic numerical study that captures the effects of initial geometries using a two-dimensional axisymmetric model. The results show that geometries with higher curvatures result in deeper melt pools and higher surface displacement because higher fluid velocities aid the convection heat transfer. Additionally, we define a modified capillary number (CaM) which elegantly captures these effects.

A Steady State Semi-analytical Approximation of Melt Pool Evolution in Pulsed Laser Surface Melting

Pulsed laser surface melting (pLSM) is a technique that offers an efficient and effective way to modify the geometry surfaces without any addition or removal of material. The resultant surface geometry plays a critical role in several applications. This paper presents a steady-state thin-film approximation of the melt pool created by pLSM and the resulting semi-analytical solution for the evolved surface geometry. These predictions of the semi-analytical solution are then compared with a validated numerical solution. The comparison demonstrates a good match with errors ranging from ~4% to ~25% across several pulse duration. Larger errors are observed at comparatively lower and higher pulse duration, and smaller errors are observed for intermediate pulse duration values. Overall, the thin film solution is a reasonable and useful approximation of the evolved surface geometry through the pLSM process, thus saving significant computational costs.