Hydrodynamic Instability Induces Spontaneous Motion of Floating Ice Discs
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866915622457180160 |
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| author | Li, Min Zhu, Lailai |
| author_facet | Li, Min Zhu, Lailai |
| contents | Spinning ice discs in nature have been reported for more than a century, yet laboratory experiments have yielded diverse observations and contradictory explanations, leaving the mechanism behind the disc motion elusive. Here we combine numerical simulations and scaling analysis to investigate a freely moving ice disc in a lab-scale water tank. We observe the disc remaining stationary or experiencing spontaneous motion, depending on the disc-water temperature difference and water depth. The motion is initiated by a buoyancy-driven, downward plume arising from water's density anomaly -- its density peaks near $4^\circ$C. Crucially, the plume breaks rotational and mirror symmetries after descending beyond a critical distance due to a thermoconvective instability, thereby inducing the disc to move autonomously. Our findings quantitatively unify disc behaviors observed across independent experiments and establish a predictive criterion for the onset of disc motion. More broadly, we point to a route for thermally-driven transport: coupling of bulk thermoconvection and moving bodies, relevant to geophysical processes such as continental drift and iceberg capsizing. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2511_13184 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Hydrodynamic Instability Induces Spontaneous Motion of Floating Ice Discs Li, Min Zhu, Lailai Fluid Dynamics Spinning ice discs in nature have been reported for more than a century, yet laboratory experiments have yielded diverse observations and contradictory explanations, leaving the mechanism behind the disc motion elusive. Here we combine numerical simulations and scaling analysis to investigate a freely moving ice disc in a lab-scale water tank. We observe the disc remaining stationary or experiencing spontaneous motion, depending on the disc-water temperature difference and water depth. The motion is initiated by a buoyancy-driven, downward plume arising from water's density anomaly -- its density peaks near $4^\circ$C. Crucially, the plume breaks rotational and mirror symmetries after descending beyond a critical distance due to a thermoconvective instability, thereby inducing the disc to move autonomously. Our findings quantitatively unify disc behaviors observed across independent experiments and establish a predictive criterion for the onset of disc motion. More broadly, we point to a route for thermally-driven transport: coupling of bulk thermoconvection and moving bodies, relevant to geophysical processes such as continental drift and iceberg capsizing. |
| title | Hydrodynamic Instability Induces Spontaneous Motion of Floating Ice Discs |
| topic | Fluid Dynamics |
| url | https://arxiv.org/abs/2511.13184 |