Multidirectional solidification model for the description of micropore formation in spray deposition processes

This article describes a numerical investigation of micropore formation in solidifying molten metal droplets impinging on a colder substrate. The velocity field inside the spreading liquid droplet is computed as a solution of the incompressible Navier-Stokes equations, and a volume-of-fluid function is defined in order to track the location of the free surface. A multidirectional solidification model is implemented to simulate the formation of possible pores, cavities, and/or troughs. This tracking algorithm allows for complex interface morphology representation as well as interface merging simulation. In the test case considered (high-velocity impact of a single droplet), simulations predict the formation of an annular trough on the surface of the solidified splat. This feature may be a precursor of pore or cavity formation in multiple-droplet cases.