Simulation of liquid-jet overflow in droplet deposition processes

Porosity formation in spray deposition processes is investigated. The empha sis is on one possible mechanism of micro-pore formation during droplet spr eading and solidification: liquid-jet overflow. To this end, the Navier-Sto kes equations are solved numerically using finite differences and the free surface is tracked using the Volume of Fluid (VOF) method. A previously dev eloped multi-directional solidification algorithm is adapted and implemente d in the Navier-Stokes solver to perform numerical simulations of liquid-me tal droplet impact, spreading, and solidification. The results obtained all ow a detailed description of the liquid-jet overflow mechanism and of the r esulting solidified disk morphology. The influence of the Weber and Reynold s numbers, the solidification constant, and the contact angle are investiga ted. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.