Abstract
This paper presents a direct numerical simulation of solidification of a molten metal drop on a cold plate with various wettability by an axisymmetric front-tracking method. Because of the plate kept at a temperature below the fusion value of the melt, a thin solid layer forms at the plate and evolves upwards. The numerical results show that the solidifying front is almost flat except near the triple point with a high solidification rate at the beginning and final stages of solidification. Two solid-to-liquid density ratios ρsl = 0.9 (volume change) and 1.0 (no change in volume), with two growth angles φ0 = 0° and 12° are considered. The presence of volume change and a non-zero growth angle results in a solidified drop with a conical shape at the top. The focusing issue is the effects of the wettability of the plate in terms of the contact angle φ0. Increasing the contact angle in the range of 45° to 120° increases time for completing solidification, i.e., solidification time. However, it has a minor effect on the conical angle at the top of the solidified drop and the difference between the initial liquid and final solidified heights of the drop. The effects of the density ratio and growth angle are also presented.
Highlights
Liquid–solid phase change process in drops sessile on a cold solid surface has been of important interest in recent years due to its wide appearance in nature and engineering problems such as water drops freezing on wind turbine blades and electric cables, and metal drops solidifying in the crystallization and atomization processes
They found that the contact angle has a remarkable effect on the water drop freezing time: it increases with an increase in the contact angle
It is evident that detailed direct numerical simulations of the solidification process of a molten metal drop under the effect of the contact angle are rarely found in the literature
Summary
Liquid–solid phase change process in drops sessile on a cold solid surface has been of important interest in recent years due to its wide appearance in nature and engineering problems such as water drops freezing on wind turbine blades and electric cables, and metal drops solidifying in the crystallization and atomization processes. The model results have not shown conical shapes observed in the experiments In another theoretical work [14], the author developed a model to simulate the freezing behaviors of a water drop on a cold plate. It is evident that detailed direct numerical simulations of the solidification process of a molten metal drop (i.e., with the Prandtl number of around 0.01) under the effect of the contact angle are rarely found in the literature This gap motivates our present study since the problem is extremely important in academia and in nature and engineering applications [10,11,12,20,21]. The method used is an axisymmetric front tracking/finite difference technique [22,23]
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