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259 results on '"Rempel, Alan"'

3. The generalized Clapeyron equation and its application to confined ice growth

Author

Style, Robert W., Gerber, Dominic, Rempel, Alan W., and Dufresne, Eric R.

Subjects
Condensed Matter - Soft Condensed Matter, Physics - Geophysics
Abstract

Most theoretical descriptions of stresses induced by freezing are rooted in the (generalized) Clapeyron equation, which predicts the pressure that a solid can exert as it cools below its melting temperature. This equation is central for topics ranging beyond glaciology to geomorphology, civil engineering, food storage, and cryopreservation. However, it has inherent limitations, requiring isotropic solid stresses and conditions near bulk equilibrium. Here, we examine when the Clapeyron equation is applicable by providing a rigorous derivation that details all assumptions. We demonstrate the natural extension for anisotropic stress states, and we show how the temperature and pressure ranges for validity depend on well-defined material properties. Finally, we demonstrate how the range of applicability of the (linear) Clapeyron equation can be extended by adding higher-order terms, yielding results that are in good agreement with experimental data for the pressure melting of ice., Comment: 2 Figures

Published
2023
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4. Enzymatic Hydrolysis of Microalgal Biomass

Author

Maria Colla, Luciane, primary, Simon, Viviane, additional, Felipe Freitag, João, additional, Fagundes, Victória Dutra, additional, Rempel, Alan, additional, and Arenhart Braun, Julia Catiane, additional

Published
2024
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5. A thermomechanical model for frost heave and subglacial frozen fringe

Author

Meyer, Colin R., Schoof, Christian, and Rempel, Alan W.

Subjects
Physics - Fluid Dynamics, Physics - Geophysics
Abstract

Ice-infiltrated sediment, known as a frozen fringe, leads to phenomena such as frost heave, ice lenses, and meters of debris-rich ice under glaciers. Understanding the dynamics of frozen fringe development is important as frost heave is responsible for damaging infrastructure at high latitudes and frozen sediments at the base of glaciers can modulate glacier flow, influencing the rate of global sea level rise. Here we study the fluid physics of interstitial freezing water in sediments and focus on the conditions relevant for subglacial environments. We describe the thermomechanics of liquid water flow through and freezing in ice-saturated frozen sediments. The force balance that governs the frozen fringe thickness depends on the weight of the overlying material, the thermomolecular force between ice and sediments across premelted films of liquid, and the water pressure within liquid films that is required by flow according to Darcy's law. We combine this mechanical model with an enthalpy method which conserves energy across phase change interfaces on a fixed computational grid. The force balance and enthalpy model together determine the evolution of the frozen fringe thickness and our simulations predict frost heave rates and ice lens spacing. Our model accounts for premelting at ice-sediment contacts, partial ice saturation of the pore space, water flow through the fringe, the thermodynamics of the ice-water-sediment interface, and vertical force balance. We explicitly account for the formation of ice lenses, regions of pure ice that cleave the fringe at the depth where the interparticle force vanishes. Our model results allow us to predict the thickness of a frozen fringe and the spacing of ice lenses at the base of glaciers., Comment: 25 pages, 7 figures, 1 appendix

Published
2021

18. Application of Biochar for Soil Remediation

Author

Rempel, Alan, Nazari, Mateus Torres, Braun, Julia Catiane Arenhart, Kreling, Naiara Elisa, Treichel, Helen, Colla, Luciane Maria, Thapar Kapoor, Riti, editor, Treichel, Helen, editor, and Shah, Maulin P., editor

Published
2021
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25. Waste Biomass and Blended Bioresources in Biogas Production

Author

Colla, Luciane Maria, Margarites, Ana Cláudia Freitas, Decesaro, Andressa, Magro, Francisco Gerhardt, Kreling, Naiara, Rempel, Alan, Machado, Thaís Strieder, Gupta, Vijai Kumar, Series Editor, Tuohy, Maria G., Series Editor, Treichel, Helen, editor, and Fongaro, Gislaine, editor

Published
2019
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31. Techniques and mechanisms of bacteria immobilization on biochar for further environmental and agricultural applications

Author

Schommer, Vera Analise, primary, Nazari, Mateus Torres, additional, Melara, Flávia, additional, Braun, Julia Catiane Arenhart, additional, Rempel, Alan, additional, dos Santos, Lara Franco, additional, Ferrari, Valdecir, additional, Colla, Luciane Maria, additional, Dettmer, Aline, additional, and Piccin, Jeferson Steffanello, additional

Published
2023
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35. Challenges and opportunities for third-generation ethanol production: A critical review

Author

Müller, Caroline, primary, Scapini, Thamarys, additional, Rempel, Alan, additional, Abaide, Ederson Rossi, additional, Camargo, Aline Frumi, additional, Nazari, Mateus Torres, additional, Tadioto, Viviani, additional, Bonatto, Charline, additional, Tres, Marcus Vinícius, additional, Zabot, Giovani Leone, additional, Colla, Luciane Maria, additional, Treichel, Helen, additional, and Alves, Sérgio Luiz, additional

Published
2023
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41. Frost

Author

Rempel, Alan W., Singh, Vijay P., editor, Singh, Pratap, editor, and Haritashya, Umesh K., editor

Published
2011
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42. A thermomechanical model for frost heave and subglacial frozen fringe.

Author

Meyer, Colin R., Schoof, Christian, and Rempel, Alan W.

Subjects
FROST heaving, LIQUID films, ENERGY conservation, MECHANICAL models, SEA level, ELASTOHYDRODYNAMIC lubrication
Abstract

Ice-infiltrated sediment, or frozen fringe, is responsible for phenomena such as frost heave, ice lenses and metres of debris-rich ice under glaciers. Understanding frozen fringes is important as frost heave is responsible for damaging infrastructure at high latitudes and sediment freeze-on at the base of glaciers can modulate subglacial friction, influencing the rate of global sea level rise. Here we describe the thermomechanics of liquid water flow and freezing in ice-saturated sediments, focusing on the conditions relevant for subglacial environments. The force balance that governs the frozen fringe thickness depends on the weight of the overlying material, the thermomolecular force between ice and sediments across liquid premelted films and the water pressure required by Darcy flow. We combine this mechanical model with an enthalpy method that conserves energy across phase change interfaces on a fixed computational grid. The force balance and enthalpy model together determine the evolution of the frozen fringe thickness and our simulations predict frost heave rates and ice lens spacing. Our model accounts for premelting at ice–sediment contacts, partial ice saturation of the pore space, water flow through the fringe, the thermodynamics of the ice–water–sediment interface and vertical force balance. We explicitly account for the formation of ice lenses, regions of pure ice that cleave the fringe at the depth where the interparticle force vanishes. Our model results allow us to predict the thickness of a frozen fringe and the spacing of ice lenses in subaerial and subglacial sediments. [ABSTRACT FROM AUTHOR]

Published
2023
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45. Thermal controls on ice stream shear margins

Author

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Hunter, Pierce, Meyer, Colin, Minchew, Brent, Haseloff, Marianne, Rempel, Alan, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Hunter, Pierce, Meyer, Colin, Minchew, Brent, Haseloff, Marianne, and Rempel, Alan

Abstract

AbstractIce stream discharge responds to a balance between gravity, basal friction and lateral drag. Appreciable viscous heating occurs in shear margins between ice streams and adjacent slow-moving ice ridges, altering the temperature-dependent viscosity distribution that connects lateral drag to marginal strain rates and ice stream velocity. Warmer ice deforms more easily and accommodates faster flow, whereas cold ice supplied from ice ridges drives advective cooling that counteracts viscous heating. Here, we present a two-dimensional (three velocity component), steady-state model designed to explore the thermal controls on ice stream shear margins. We validate our treatment through comparison with observed velocities for Bindschadler Ice Stream and verify that calculated temperatures are consistent with results from previous studies. Sweeping through a parameter range that encompasses conditions representative of ice streams in Antarctica, we show that modeled steady-state velocity has a modest response to different choices in forcing up until temperate zones develop in the shear margins. When temperate zones are present, velocity is much more sensitive to changes in forcing. We identify key scalings for the emergence of temperate conditions in our idealized treatment that can be used to identify where thermo-mechanical feedbacks influence the evolution of the ice sheet.

Published
2022

46. Diffuse debris entrainment in glacier, lab and model environments.

Author

Rempel, Alan W., Hansen, Dougal D., Zoet, Luke K., and Meyer, Colin R.

Subjects
*GLACIERS, *POTENTIAL flow, *COLD (Temperature), *CRYSTAL grain boundaries, *LOW temperatures, *ICE, *GRAIN, *CIRCADIAN rhythms
Abstract

Small quantities of liquid water lining triple junctions in polycrystalline glacier ice form connected vein networks that enable material exchange with underlying basal environments. Diffuse debris concentrations commonly observed in ice marginal regions might be attributed to this mechanism. Following recent cryogenic ring-shear experiments, we observed emplacement along grain boundaries of loess particles several tens of microns in size. Here, we describe an idealized model of vein liquid flow to elucidate conditions favoring such particle transport. Gradients in liquid potential drive flow toward colder temperatures and lower solute concentrations, while deviations of the ice stress state from hydrostatic balance produce additional suction toward anomalously low ice pressures. Our model predicts particle entrainment following both modest warming along the basal interface resulting from anticipated natural changes in effective stress, and the interior relaxation of temperature and solute concentration imposed by our experimental protocols. Comparisons with experimental observations are encouraging, but suggest that liquid flow rates are somewhat higher and/or more effective at dragging larger particles than predicted by our idealized model with nominal parameter choices. Diffuse debris entrainment extending several meters above the glacier bed likely requires a more sophisticated treatment that incorporates effects of ice deformation or other processes. [ABSTRACT FROM AUTHOR]

Published
2023
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