Impact and solidification of tin droplets on a flat stainless steel substrate was studied using both experiments and numerical simulation. In the experiments tin droplets (2.1 mm diameter) were formed and dropped onto a stainless steel surface whose remperature was varied from 25°C to 240°C. Impact of droplets,was photographed, and evolution of droplet spread diameter and liquid-solid contact angle measured from photographs. A complete numerical solution of the Navier-Stokes and energy equations, based on a modified SOLA-VOF method, was used to model droplet deformation and solidification and heat transfer in the substrate. Measured values of liquid-solid contact angle were used as a boundary condition for the numerical model. Values of the thermal contact resistance at the droplet-substrate interface were estimated by matching numerical predictions of substrate temperature variation and droplet contact diameter with experimental measurements. Comparison of computer generated images of impacting droplets with photographs for all three cases showed that the numerical model correctly modeled droplet shape during deformation and solidification.

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