ARTICLE:

• THREE DIMENSIONAL PRESOLIDIFICATION HEAT TRANSFER AND FLUID DYNAMICS IN MOLTEN MICRODROPLET DEPOSITION  download article

V. Butty
Institute of Energy Technology, Laboratory of Thermodynamics in Emerging Technologies, Swiss Federal Institute of Technology, ETH Center, 8092 Zurich, Switzerland

Dimos Poulikakos
Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, Institute of Energy Technology, Swiss Federal Institute of Technology (ETH), ETH Center, Zurich, Switzerland

J. Giannakouros
Institute of Energy Technology, Laboratory of Thermodynamics in Emerging Technologies, Swiss Federal Institute of Technology, ETH Center, 8092 Zurich, Switzerland

ABSTRACT

The non-axisymmetric, coupled fluid mechanics and heat transfer of an impacting liquid solder droplet on a flat substrate is being investigated numerically using the finite element method. The modelling of the fluid mechanics is based upon the full laminar Navier-Stokes equations employing a Lagrangian frame of reference. Due to the large droplet deformation, the surface (skin) as well as the volumetric mesh have to be regenerated during the calculations in order to maintain the high accuracy of the numerical scheme. The pressure and velocity fields are then interpolated on the newly created mesh. The energy equation is solved in both the droplet and the substrate domain. Since the meshes of the droplet and the substrate are not connected, a time and space averaged thermal contact resistance is implemented in order to link the two thermal domains. For the impact parameters used in this study (We = 2.38, Fr = 16300, Re = 157, Ma = 0.001), the droplet rolls along the substrate but its shape remains practically axisymmetric for all the impact angles within the range from 0 to 60 [deg.]. The substrate/droplet contact area is not a monotonically decreasing function of time and the cooling of the droplet is markedly dependent on the impact angle.

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317-324 pages

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