A study of ice formation in stationary turbulent conditions is carried out in various limit regimes of crystal growth, supercooling and ice entrainment at the water surface. Analytical expressions for the temperature, salinity and ice concentration mean profiles are provided, and the role of fluctuations in ice production is numerically quantified. Lower bounds on the ratio of sensible heat flux to latent heat flux to the atmosphere are derived and their dependence on key parameters such as salt restitution in freezing and ice entrainment in the water column is elucidated.
Surface icing affects the safety and performance of numerous processes in technology. Previous studies mostly investigated freezing of individual droplets. The interaction among multiple droplets during freezing is investigated less, especially on nanotextured icephobic surfaces, despite its practical importance as water droplets never appear in isolation, but in groups. Here we show that freezing of a supercooled droplet leads to spontaneous self-heating and induces strong vaporization. The resulting, rapidly propagating vapor front causes immediate cascading freezing of neighboring supercool…
Statistical orientation and distribution of columnar ice crystals in turbulent flows
CNRS, Ecole Normale Superieure de Lyon（法国国家科学研究中心，里昂高等师范学院）；Max Planck Institute for Dynamics and Self-Organization（马克斯·普朗克动力学与自组织研究所）；University of Engineering and Technology Lahore（拉合尔工程技术大学）；Gothenburg University（哥德堡大学）；Ecole Centrale de Lyon（里昂中央理工学院）
Increased knowledge about wave attenuation processes in sea ice, and hence atmosphere-wave-ice-ocean energy transfer, is necessary to improve sea ice dynamics models used for climate modeling and offshore applications. The aim of this study is to generate such much needed data by investigating colliding ice floes dynamics in a large-scale experiment and directly measuring and quantifying the turbulent kinetic energy (TKE). The field work was carried out at Van Mijen Fjord on Svalbard, where a 3x4 m ice floe was sawed out in the fast ice. Wave motion was simulated by pulling the ice floe back a…
The ratio of heat and salt flux is employed in ice-ocean models to represent ice-ocean interactions. In this study, this flux ratio is determined from direct numerical simulations of free convection beneath a melting, horizontal, smooth ice-ocean interface. We find that the flux ratio at the interface is three times as large as previously assessed based on turbulent-flux measurements in the field. As a consequence, interface salinities and melt rates are overestimated by up to 40\% if they are based on the three-equation formulation. We also find that the interface flux ratio depends only very…
Several phenomena are known to attenuate waves in the marginal ice zone, such as wave scattering due to ice floes, viscous dissipation inside the ice and energy dissipation caused by ice floe interactions. Our aim of this study is to investigate colliding ice floes and to quantify the Turbulent Kinetic Energy (TKE) dissipation in the surrounding water through direct observations. The field work was carried out in Van Mijen Fjord on Svalbard, where an artificial 3x4 m^2 ice floe was sawed out in the 1 m thick ice. Wave motion was simulated by pulling the ice floe back and forth in an oscillator…
The aim of this note is to derive the mixed-phase version of the moist-air entropy potential temperature $θ_s$ derived in Marquet (2011). This mixed-phase version is suitable to describe parcels where liquid water and ice are allowed to coexist, with possible under- or super-saturations, with possible supercooled water and with possible different temperatures for dry air and water vapour, on the one hand, condensed water and ice, on the other hand. The impact of this new mixed-phase version for $θ_s$ are evaluated by using high latitudes, SHEBA/FIRE-ACE vertical profiles depicted in Figure 7 o…
Subglacial lakes are isolated, cold-temperature and high-pressure water environments hidden under ice sheets, which might host extreme microorganisms. Here, we use two-dimensional direct numerical simulations in order to investigate the characteristic temperature fluctuations and velocities in freshwater subglacial lakes as functions of the ice overburden pressure, $p_i$, the water depth, $h$, and the geothermal flux, $F$. Geothermal heating is the unique forcing mechanism as we consider a flat ice-water interface. Subglacial lakes are fully convective when $p_i$ is larger than the critical pr…
Sublimation of drifting snow, which is significant for the balances of mass and energy of the polar ice sheet, is a complex physical process with intercoupling between ice crystals, wind field, temperature, and moisture. Here a three-dimensional drifting snow sublimation model in a turbulent boundary layer is proposed. In contrast to most previous models, it takes into account turbulent diffusion of moisture from lower to higher elevations, allowing the air humidity near the surface to be undersaturated and thus sublimation to occur. From simulations with this model, we find that snow sublimat…
Motivated by the ablation of vertical ice faces in salt water, we use three-dimensional direct numerical simulations to investigate the heat and salt fluxes in two-scalar vertical convection. For parameters relevant to ice-ocean interfaces in the convection-dominated regime, we observe that the salinity field drives the convection and that heat is essentially transported as a passive scalar. By varying the diffusivity ratio of heat and salt (i.e., the Lewis number $Le$), we identify how the different molecular diffusivities affect the scalar fluxes through the system. Away from the walls, we f…
Trapped beneath the Antarctic ice sheet lie over 400 subglacial lakes, which are considered to be extreme, isolated, yet viable habitats for microbial life. The physical conditions within subglacial lakes are critical to evaluating how and where life may best exist. Here, we propose that Earth's geothermal flux provides efficient stirring of Antarctic subglacial lake water. We demonstrate that most lakes are in a regime of vigorous turbulent vertical convection, enabling suspension of spherical particulates with diameters up to 36 micrometers. Thus, dynamic conditions support efficient mixing …
