Fast Dynamics of Water Droplets Freezing from the Outside In

Sander Wildeman, Sebastian Sterl, Chao Sun, Detlef Lohse

Research output: Contribution to journalArticleAcademicpeer-review

22 Citations (Scopus)
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Abstract

A drop of water that freezes from the outside in presents an intriguing problem: the expansion of water upon freezing is incompatible with the self-confinement by a rigid ice shell. Using high-speed imaging we show that this conundrum is resolved through an intermittent fracturing of the brittle ice shell and cavitation in the enclosed liquid, culminating in an explosion of the partially frozen droplet. We propose a basic model to elucidate the interplay between a steady buildup of stresses and their fast release. The model reveals that for millimetric droplets the fragment velocities upon explosion are independent of the droplet size and only depend on material properties (such as the tensile stress of the ice and the bulk modulus of water). For small (submillimetric) droplets, on the other hand, surface tension starts to play a role. In this regime we predict that water droplets with radii below 50μm are unlikely to explode at all. We expect our findings to be relevant in the modeling of freezing cloud and rain droplets.
Original languageEnglish
Article number084101
Number of pages5
JournalPhysical review letters
Volume118
Issue number8
DOIs
Publication statusPublished - 24 Feb 2017

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freezing
ice
water
explosions
fracturing
rain
cavitation flow
tensile stress
bulk modulus
interfacial tension
high speed
fragments
radii
expansion
liquids

Cite this

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title = "Fast Dynamics of Water Droplets Freezing from the Outside In",
abstract = "A drop of water that freezes from the outside in presents an intriguing problem: the expansion of water upon freezing is incompatible with the self-confinement by a rigid ice shell. Using high-speed imaging we show that this conundrum is resolved through an intermittent fracturing of the brittle ice shell and cavitation in the enclosed liquid, culminating in an explosion of the partially frozen droplet. We propose a basic model to elucidate the interplay between a steady buildup of stresses and their fast release. The model reveals that for millimetric droplets the fragment velocities upon explosion are independent of the droplet size and only depend on material properties (such as the tensile stress of the ice and the bulk modulus of water). For small (submillimetric) droplets, on the other hand, surface tension starts to play a role. In this regime we predict that water droplets with radii below 50μm are unlikely to explode at all. We expect our findings to be relevant in the modeling of freezing cloud and rain droplets.",
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Fast Dynamics of Water Droplets Freezing from the Outside In. / Wildeman, Sander; Sterl, Sebastian; Sun, Chao ; Lohse, Detlef .

In: Physical review letters, Vol. 118, No. 8, 084101, 24.02.2017.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Fast Dynamics of Water Droplets Freezing from the Outside In

AU - Wildeman, Sander

AU - Sterl, Sebastian

AU - Sun, Chao

AU - Lohse, Detlef

PY - 2017/2/24

Y1 - 2017/2/24

N2 - A drop of water that freezes from the outside in presents an intriguing problem: the expansion of water upon freezing is incompatible with the self-confinement by a rigid ice shell. Using high-speed imaging we show that this conundrum is resolved through an intermittent fracturing of the brittle ice shell and cavitation in the enclosed liquid, culminating in an explosion of the partially frozen droplet. We propose a basic model to elucidate the interplay between a steady buildup of stresses and their fast release. The model reveals that for millimetric droplets the fragment velocities upon explosion are independent of the droplet size and only depend on material properties (such as the tensile stress of the ice and the bulk modulus of water). For small (submillimetric) droplets, on the other hand, surface tension starts to play a role. In this regime we predict that water droplets with radii below 50μm are unlikely to explode at all. We expect our findings to be relevant in the modeling of freezing cloud and rain droplets.

AB - A drop of water that freezes from the outside in presents an intriguing problem: the expansion of water upon freezing is incompatible with the self-confinement by a rigid ice shell. Using high-speed imaging we show that this conundrum is resolved through an intermittent fracturing of the brittle ice shell and cavitation in the enclosed liquid, culminating in an explosion of the partially frozen droplet. We propose a basic model to elucidate the interplay between a steady buildup of stresses and their fast release. The model reveals that for millimetric droplets the fragment velocities upon explosion are independent of the droplet size and only depend on material properties (such as the tensile stress of the ice and the bulk modulus of water). For small (submillimetric) droplets, on the other hand, surface tension starts to play a role. In this regime we predict that water droplets with radii below 50μm are unlikely to explode at all. We expect our findings to be relevant in the modeling of freezing cloud and rain droplets.

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