Bulletin of the American Physical Society
73rd Annual Meeting of the APS Division of Fluid Dynamics
Sunday–Tuesday, November 22–24, 2020; Virtual, CT (Chicago time)
Session U07: Geophysical Fluid Dynamics: Cryosphere (8:45am  9:30am CST)Interactive On Demand

Hide Abstracts 

U07.00001: Melting driven by Rotating RayleighB\'enard Convection S. Ravichandran, John S. Wettlaufer We study numerically the melting of a horizontal layer of a pure solid above a convecting layer of its fluid rotating about the vertical axis. In the rapidly rotating regime, and for the Rayleigh numbers of order $10^7$ considered here, convection takes the form of columnar vortices. Since these vortices transport heat from the bottom surface to the upper boundary, the melt pattern reflects the number and size of the columnar vortices, which in turn depend on the Prandtl, Reynolds, Rossby and Stefan numbers of the system, and on whether we treat periodic or confined horizontal geometries. We study how the morphology of the phase boundary, as well as the overall rate of melting, vary with the system parameters. For large values of the latent heat of fusion, we find that the vertical convective heat flux and the melt rate balance each other and reach constant maximal values over long time intervals. Concurrently, the interfacial roughness is also maximal, independent of the flow parameters. The confluence of processes responsible for the range of phase boundary geometries found should influence the treatment of moving boundary problems in mathematical models, particularly when rotational effects are important. Preprint: arXiv:2007.12751 [Preview Abstract] 

U07.00002: Impurity effects in thermal regelation. navaneeth kizhakke marath, John Wettlaufer When a particle is placed in a material with a lower bulk melting temperature, intermolecular forces can lead to the existence of a ``premelted'' liquid film of the lower melting temperature material. Despite the system being below the melting temperatures of both solids, the liquid film is a consequence of thermodynamic equilibrium, controlled by intermolecular, ionic and other interactions. An imposed temperature gradient drives the translation of the particle by a process of melting and refreezing known as ``thermal regelation''. We calculate the rate of regelation of spherical particles surrounded by premelted films that contain ionic impurities. The impurities enhance the rate of motion thereby influencing the dynamics of single particles and distributions of particles, which we describe in addition to the consequences of it in the context of dating of ice cores. [Preview Abstract] 

U07.00003: How does iceberg shape affect melting? Eric Hester, Craig McConnochie, Claudia Cenedese, LouisAlexandre Couston, Benjamin Favier, Keaton Burns, Geoffrey Vasil Iceberg melting is a critical freshwater flux from the cryosphere to oceans. Global climate simulations require simple and accurate parameterisations of the melting process, but most models still neglect many relevant details. Iceberg shape is an important but challenging aspect to include in models of melting. Icebergs come in enormously different shapes and sizes, and distinct processes dominate basal and side melting. We show how different aspect ratios and water velocities affect melting using combined experimental and numerical studies in warm salt water. We find that existing parameterisations misrepresent many aspects of iceberg melting. Our experiments reveal significant variations in melting within and between iceberg faces. We reproduce and explain these effects with novel multiphysics numerical simulations. Buoyancy is subdominant for high flow rates, and there is significant variation in basal melting. Buoyancy matters much more for low flow rates, where doublediffusive effects become important. We propose several improvements to capture these effects in parameterisations of iceberg melting. [Preview Abstract] 

U07.00004: Emerging Arctic Ocean turbulence revealed by rotating sea ice floes. Rosalinda Lopez, Georgy E. Manucharyan, Monica M. Wilhelmus Mesoscale eddies are hypothesized to be a crucial component of the dynamics of the Beaufort Gyre (BG). Yet, comprehensive observations of these structures are currently missing. In this talk, we reveal the strong relationship between the rotation rates of noninteracting sea ice and the critical parameters of the underlying ocean eddy field. To this end, we used our recently developed sea ice Lagrangian tracking algorithm to automatically process daily satellite remote sensing optical imagery. We quantified the rotation rate and interannual variability of over 20,000 noninteracting ice plates, with length scales ranging from 4 to 80 km, between the summers of 2003 and 2019. We demonstrate that the observed statistical dependence of the ice plate rotation rates on their sizes can be accurately reproduced using an idealized quasigeostrophic eddy field to drive the evolution of the ice plates. Leveraging the robust relationship between sea ice rotation and the turbulent eddy field, we provide the first observational evidence of the monotonic relation between the strength of the largescale mean flow of the BG and the corresponding eddy field. Our findings, therefore, directly support the hypothesis of the pertinence of eddymean flow interactions in the BG. [Preview Abstract] 

U07.00005: Sea Ice Dispersion Driven by Fluctuating Wind and Ocean Currents Bryan Shaddy, Bhargav Rallabandi The motion of sea ice is driven by wind and ocean currents and comprises both a steady drift and a fluctuating component. Here, we systematically describe the relation between sea ice dispersion and environmental noise starting from a Lagrangian description of noninteracting ice floes. We quantify the nonlinear dynamics of sea ice through stochastic simulations, accounting for noise in wind and ocean currents, in addition to Coriolis forces. The ice follows dispersive behavior on time scales on the order of days, consistent with observations. We find that the dispersion coefficient and the mean square velocity of the ice depend strongly on the direction of mean ocean currents relative to the wind as well as a dimensionless Coriolis parameter involving the ice thickness. We then develop a linearized Langevinlike framework which maps the dynamics of sea ice to that of a stochastically forced damped harmonic oscillator, yielding analytic insight into the ice dispersion statistics. Our results are useful in quantifying sea ice properties under known environmental conditions, or alternatively as a way to use wind data and sea ice images to infer ocean statistics. [Preview Abstract] 

U07.00006: Nonlinear interactions between an unstably stratified shear flow and an evolving phase boundary Srikanth Toppaladoddi Well resolved numerical simulations are used to study RayleighB\'enardPoiseuille flow over an evolving phase boundary for moderate values of P\'eclet ($Pe \in \left[0, 200\right]$) and Rayleigh ($Ra \in \left[2.15 \times 10^3, 10^6\right]$) numbers. The relative effects of mean shear and buoyancy are quantified using a bulk Richardson number: $Ri_b = Ra \cdot Pr/Pe^2$, where $Pr$ is the Prandtl number. For $Ri_b \ll 1$, we find that the Poiseuille flow inhibits convective motions, resulting in the heat transport being only due to conduction. In the opposite limit of $Ri_b \gg 1$, the flow properties and heat transport closely correspond to the purely convective case. We also find that for $Ri_b = O(1)$ there is a pattern competition for convection cells with a preferred aspect ratio. Furthermore, we find travelling waves at the solidliquid interface when $Pe \neq 0$, in qualitative agreement with other sheared convective flows in the experiments of Gilpin \emph{et al.} (\emph{J. Fluid Mech} {\bf 99}(3), pp. 619640, 1980) and the linear stability analysis of Toppaladoddi and Wettlaufer (\emph{J. Fluid Mech.} {\bf 868}, pp. 648665, 2019). [Preview Abstract] 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2021 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700