Abrupt transition from slow to fast melting of ice

Self Cite

The presence of salt in seawater strongly affects the melt rate and the shape evolution of ice, both of utmost relevance in ice–ocean interactions and thus for the climate. To get a better quantitative understanding of the physical mechanics at play in ice melting in salty water, we numerically investigate the lateral melting of an ice block in stably stratified saline water. The developing ice shape from our numerical results shows good agreement with the experiments and theory from Huppert & Turner (J. Fluid Mech., vol. 100, 1980, pp. 367–384). Furthermore, we find that the melt rate of ice depends non-monotonically on the mean ambient salinity: it first decreases for increasing salt concentration until a local minimum is attained, and then increases again. This non-monotonic behaviour of the ice melt rate is due to the competition among salinity-driven buoyancy, temperature-driven buoyancy and salinity-induced stratification. We develop a theoretical model based on the force balance which gives a prediction of the salt concentration for which the melt rate is minimal, and is consistent with our data. Our findings give insight into the interplay between phase transitions and double-diffusive convective flows.

Section: Physical Mechanism Of the Dependence Of The Average Melt Rat...mentioning

confidence: 95%

“…2021; Yang et al. 2022 a ). Layered structures on the melt front are observed and quantitatively agree with the experiments of Huppert & Turner (1980).…”

Section: Introductionmentioning

confidence: 99%

Ice melting in salty water: layering and non-monotonic dependence on the mean salinity

Yang,

Howland,

Liu

et al. 2023

Self Cite

“…Various lab experiments and direct numerical simulations have been conducted to investigate the interaction between ice melting and ambient flow in the laboratory scale, including ice melting in still and flowing water (Dumore, Merk & Prins 1953;Vanier & Tien 1970;Hao & Tao 2002;Hester et al 2021;Weady et al 2022), in Rayleigh-Bénard convection (Davis, Müller & Dietsche 1984;Dietsche & Müller 1985;Esfahani et al 2018;Favier, Purseed & Duchemin 2019;Yang et al 2023b), which involves a plate being heated from below and a plate being cooled from above (Lohse & Xia 2010;Ecke & Shishkina 2023), and in vertical convection (Wang et al 2021c;Yang et al 2022). The density anomaly effect in freshwater, combined with inclination, causes distinct flow regimes and ice melting morphology under different temperatures, which has been comprehensively investigated by Wang, Calzavarini & Sun (2021a), Wang et al (2021b,c).…”

Section: Introductionmentioning

confidence: 99%

Shape effect on solid melting in flowing liquid

Yang,

Howland,

Liu

et al. 2024

Self Cite

Iceberg melting is a critical factor for climate change. However, the shape of an iceberg is an often neglected aspect of its melting process. Our study investigates the influence of different ice shapes and ambient flow velocities on melt rates by conducting direct numerical simulations of a simplified system of bluff body flow. Our study focuses on the ellipsoidal shape, with the aspect ratio as the control parameter. We found the shape plays a crucial role in the melting process, resulting in significant variations in the melt rate between different shapes. Without flow, the optimal shape for a minimal melt rate is the disk (two-dimensional) or sphere (three-dimensional), due to the minimal surface area. However, as the ambient flow velocity increases, the optimal shape changes with the aspect ratio. We find that ice with an elliptical shape (when the long axis is aligned with the flow direction) can melt up to 10 % slower than a circular shape when exposed to flowing water. Following the approach considered by Huang et al. (J. Fluid Mech., vol. 765, 2015, R3) for dissolving bodies, we provide a quantitative theoretical explanation for this optimal shape, based on the combined contributions from both surface-area effects and convective-heat-transfer effects. Our findings provide insight into the interplay between phase transitions and ambient flows, contributing to our understanding of the iceberg melting process and highlighting the need to consider the aspect-ratio effect in estimates of iceberg melt rates.

“…2021 d ; Yang et al. 2022), rotation (Ravichandran, Toppaladoddi & Wettlaufer 2022), initial conditions, and aspect ratio (Wang, Calzavarini & Sun 2021 b ) on fresh water freezing/melting in the RB system. However, the presence of dissolved salt in sea water adds to the complexity of the processes.…”

Section: Introductionmentioning

confidence: 99%

“…It has a laboratory scale, it is closed, and in/out energy fluxes can be measured, hence it is highly controllable, yet able to reproduce the rich process of water freezing in the presence of unsteady and turbulent flow conditions. Several recent studies have investigated the influence of temperature (Wang et al 2021c;Yang et al 2023b), inclination (Wang et al 2021d;Yang et al 2022), rotation (Ravichandran, Toppaladoddi & Wettlaufer 2022), initial conditions, and aspect ratio (Wang, Calzavarini & Sun 2021b) on fresh water freezing/melting in the RB system. However, the presence of dissolved salt in sea water adds to the complexity of the processes.…”

Section: Introductionmentioning

confidence: 99%

Sea water freezing modes in a natural convection system

Wang

Jiang

et al. 2023

Sea ice is crucial in many natural processes and human activities. Understanding the dynamical couplings between the inception, growth and equilibrium of sea ice and the rich fluid mechanical processes occurring at its interface and interior is of relevance in many domains, ranging from geophysics to marine engineering. Here we investigate experimentally the complete freezing process of water with dissolved salt in a standard natural convection system, i.e. the prototypical Rayleigh–Bénard cell. Due to the presence of a mushy phase, the studied system is considerably more complex than the freezing of fresh water in the same conditions (Wang et al., Proc. Natl Acad. Sci. USA, vol. 118, issue 10, 2021, e2012870118). We measure the ice thickness and porosity at the dynamical equilibrium state for different initial salinities of the solution and temperature gaps across the cell. These observables are non-trivially related to the controlling parameters of the system as they depend on the heat transport mode across the cell. We identify in the experiments five out of the six possible modes of heat transport. We highlight the occurrence of brine convection through the mushy ice and of penetrative convection in stably stratified liquid underlying the ice. A one-dimensional multi-layer heat flux model built on the known scaling relations of global heat transport in natural convection systems in liquids and porous media is proposed. Given the measured porosity of the ice, it allows us to predict the corresponding ice thickness, in a unified framework.