Impact of Metal Droplets: A Numerical Approach to Solidification

ORAL

Abstract

Layer-wise deposition of material to produce complex products is a subject of increasing technological relevance. Subsequent deposition of droplets is one of the possible 3d printing technologies to accomplish this. The shape of the solidified droplet is crucial for product quality. We employ the volume-of-fluid method (in the form of the open-source code Gerris) to study liquid metal (in particular tin) droplet impact. Heat transfer has been implemented based on the enthalpy approach for the liquid-solid phase. Solidification is modeled by adding a sink term to the momentum equations, reducing Navier-Stokes to Darcy's law for high solid fraction. Good agreement is found when validating the results against experimental data \footnote{S.D.Aziz, S.Chandra, Int. J. of Heat and Mass Trans. 43 (2000)}. We then map out a phase diagram in which we distinguish between solidification behavior based on Weber and Stefan number. In an intermediate impact regime impact, solidification due to a retracting phase occurs. In this regime the maximum spreading diameter almost exclusively depends on Weber number. Droplet shape oscillations lead to a broad variation of the morphology of the solidified droplet and determine the final droplet height.

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Authors

  • Robin Koldeweij

    University of Twente

  • Rajesh Mandamparambil

    TNO

  • Detlef Lohse

    University of Twente, Physic of Fluids Group, University of Twente, Physics of Fluids Group, Mesa+ Institute and J.M. Burgers Centre for Fluid Dynamics, University of Twente, The Netherlands, Physics of Fluids, MESA+ institute, University of Twente, the Netherlands, Physics of Fluids Group, University of Twente, The Netherlands, Physics of Fluids group, Faculty of Science and Technology, University of Twente, The Netherlands, Physics of Fluids, Faculty of Science \& Technology, University of Twente, The Netherlands, Physics of Fluids Group, Faculty of Science and Technology, J. M. Burgers Center for Fluid Dynamics and MESA+ Institute, University of Twente, Physics of Fluids Group, University of Twente, The Netherlands., Physics of Fluids Group, University of Twente, Physics of Fluids, University of Twente