Abstract
The Leidenfrost effect, where a drop levitates on a vapour film above a hot solid, is simulated using an efficient computational model that captures the internal flow within the droplet, models the vapour flow in a lubrication framework and is capable of resolving the dynamics of the process. The initial focus is on quasi-static droplets and the associated geometry of the vapour film formed beneath the drop, where we are able to compare with experimental analyses and assess the range of validity of the theoretical model developed in Sobac et al. (Phys. Rev. E, vol. 103, 2021, 039901). The computational model also allows us to explore parameter space, varying both the drop size and viscosity of the liquid, with computational results in excellent agreement with the theoretical model for high-viscosity liquids. Interestingly, for large water drops, discrepancies between the computational model and experiments occur, and possible reasons for this observation are provided. Our predictions reveal features including a regime with a dimpleless bottom surface of the drop and a minimum in the vapour layer thickness as a function of the drop size. Finally, the capability to simulate dynamics is revealed by computations that predict and track the vapour ‘chimney’ instability for large drops.
Highlights
When liquid drops are gently deposited on a hot solid surface whose temperature Tw is slightly above the boiling temperature Tb, the liquid boils violently resulting in rapid disappearance of the drop
To study further the influence of liquid viscosity and internal flow, in figure 6 we show the results of our computational model for drops with an initial radius R0 = 3.75 mm
A computational model has been developed that allows us to go beyond the theory of Sobac et al (2014) by taking into account internal flow and drop dynamics
Summary
When liquid drops are gently deposited on a hot solid surface whose temperature Tw is slightly above the boiling temperature Tb, the liquid boils violently resulting in rapid disappearance of the drop. If Tw is increased past the Leidenfrost temperature TL, the lifetime of the drop abruptly increases (Gottfried, Lee & Bell 1966; Biance, Clanet & Quéré 2003) due to the so-called Leidenfrost effect (Burton et al 2012; Leidenfrost 1756), where the drop levitates on its own vapour layer and is thermally shielded from the hot solid. This effect is an everyday phenomenon, seen as a water drop glides 936 A12-1. Fundamental studies of Leidenfrost drops, and numerous applications, are reviewed in great detail by Quéré (2013) and Ling & Mudwar (2017)
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