Ice shelves as floating channel flows of viscous power-law fluids
We explain the force balance in flowing marine ice sheets and the ice shelves they often feed. Treating ice as a viscous shear-thinning power law fluid, we develop an asymptotic (late-time) theory in two cases: the presence or absence of contact with sidewalls. Most real-world situations fall somewh...
Published in: | Journal of Oceanography and Marine Research |
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Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
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2016
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Online Access: | https://risweb.st-andrews.ac.uk/portal/en/researchoutput/ice-shelves-as-floating-channel-flows-of-viscous-powerlaw-fluids(a3786a15-c3a6-455e-b8cd-7035ded51c31).html https://doi.org/10.4172/2572-3103.1000150 https://research-repository.st-andrews.ac.uk/bitstream/10023/10134/1/Banik_2016_JOMR_IceShelves_CC.pdf https://arxiv.org/abs/1310.7998 https://www.esciencecentral.org/peer-reviewed/ice-shelves-as-floating-channel-flows-of-viscous-powerlaw-fluids-83254.html |
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ftunstandrewcris:oai:risweb.st-andrews.ac.uk:publications/a3786a15-c3a6-455e-b8cd-7035ded51c31 2023-05-15T16:41:56+02:00 Ice shelves as floating channel flows of viscous power-law fluids Banik, I. Dauparas, J. 2016-11-04 application/pdf https://risweb.st-andrews.ac.uk/portal/en/researchoutput/ice-shelves-as-floating-channel-flows-of-viscous-powerlaw-fluids(a3786a15-c3a6-455e-b8cd-7035ded51c31).html https://doi.org/10.4172/2572-3103.1000150 https://research-repository.st-andrews.ac.uk/bitstream/10023/10134/1/Banik_2016_JOMR_IceShelves_CC.pdf https://arxiv.org/abs/1310.7998 https://www.esciencecentral.org/peer-reviewed/ice-shelves-as-floating-channel-flows-of-viscous-powerlaw-fluids-83254.html eng eng info:eu-repo/semantics/openAccess Banik , I & Dauparas , J 2016 , ' Ice shelves as floating channel flows of viscous power-law fluids ' , Journal of Oceanography and Marine Research , vol. 4 , no. 2 , 150 . https://doi.org/10.4172/2572-3103.1000150 Glaciers Marine ice sheets Ice shelves Fluid dynamics Viscous flows Non-newtonian fluids article 2016 ftunstandrewcris https://doi.org/10.4172/2572-3103.1000150 2022-10-13T15:26:10Z We explain the force balance in flowing marine ice sheets and the ice shelves they often feed. Treating ice as a viscous shear-thinning power law fluid, we develop an asymptotic (late-time) theory in two cases: the presence or absence of contact with sidewalls. Most real-world situations fall somewhere between the two extreme cases considered. The solution when sidewalls are absent is a fairly simple generalization of that found by Robison (JFM, 648, 363). In this case, we obtain the equilibrium grounding line thickness using a simple computer model and have an analytic approximation. For shelves in contact with sidewalls, we obtain an asymptotic theory valid for long shelves. We determine when this is. Our theory is based on the velocity profile across the channel being a generalized version of Poiseuille flow, which works when lateral shear dominates the force balance. We conducted experiments using a laboratory model for ice. This was a suspension of xanthan in water, at a concentration of 0.5% by mass. The model has n ≈ 3.8, similar to that of ice. Our theories agreed extremely well with our experiments for all relevant parameters (front position, thickness profile, lateral velocity profile, longitudinal velocity gradient and grounding line thickness). We also saw detailed features similar to natural systems. Thus, we believe we have understood the dominant force balance in both types of ice shelf. Combining our understanding of the forces in the system with a basic model for basal melting and iceberg formation, we uncovered some instabilities of the natural system. Laterally confined ice shelves can rapidly disintegrate but ice tongues cannot. However, ice tongues can be shortened until they no longer exist, at which point the sheet becomes unstable and ultimately the grounding line should retreat above sea level. While the ice tongue still exists, the flow of ice into it should not be speeded up and the grounding line should also not retreat, assuming that only conditions in the ocean change. However, ... Article in Journal/Newspaper Ice Shelf Ice Shelves University of St Andrews: Research Portal Journal of Oceanography and Marine Research 04 02 |
institution |
Open Polar |
collection |
University of St Andrews: Research Portal |
op_collection_id |
ftunstandrewcris |
language |
English |
topic |
Glaciers Marine ice sheets Ice shelves Fluid dynamics Viscous flows Non-newtonian fluids |
spellingShingle |
Glaciers Marine ice sheets Ice shelves Fluid dynamics Viscous flows Non-newtonian fluids Banik, I. Dauparas, J. Ice shelves as floating channel flows of viscous power-law fluids |
topic_facet |
Glaciers Marine ice sheets Ice shelves Fluid dynamics Viscous flows Non-newtonian fluids |
description |
We explain the force balance in flowing marine ice sheets and the ice shelves they often feed. Treating ice as a viscous shear-thinning power law fluid, we develop an asymptotic (late-time) theory in two cases: the presence or absence of contact with sidewalls. Most real-world situations fall somewhere between the two extreme cases considered. The solution when sidewalls are absent is a fairly simple generalization of that found by Robison (JFM, 648, 363). In this case, we obtain the equilibrium grounding line thickness using a simple computer model and have an analytic approximation. For shelves in contact with sidewalls, we obtain an asymptotic theory valid for long shelves. We determine when this is. Our theory is based on the velocity profile across the channel being a generalized version of Poiseuille flow, which works when lateral shear dominates the force balance. We conducted experiments using a laboratory model for ice. This was a suspension of xanthan in water, at a concentration of 0.5% by mass. The model has n ≈ 3.8, similar to that of ice. Our theories agreed extremely well with our experiments for all relevant parameters (front position, thickness profile, lateral velocity profile, longitudinal velocity gradient and grounding line thickness). We also saw detailed features similar to natural systems. Thus, we believe we have understood the dominant force balance in both types of ice shelf. Combining our understanding of the forces in the system with a basic model for basal melting and iceberg formation, we uncovered some instabilities of the natural system. Laterally confined ice shelves can rapidly disintegrate but ice tongues cannot. However, ice tongues can be shortened until they no longer exist, at which point the sheet becomes unstable and ultimately the grounding line should retreat above sea level. While the ice tongue still exists, the flow of ice into it should not be speeded up and the grounding line should also not retreat, assuming that only conditions in the ocean change. However, ... |
format |
Article in Journal/Newspaper |
author |
Banik, I. Dauparas, J. |
author_facet |
Banik, I. Dauparas, J. |
author_sort |
Banik, I. |
title |
Ice shelves as floating channel flows of viscous power-law fluids |
title_short |
Ice shelves as floating channel flows of viscous power-law fluids |
title_full |
Ice shelves as floating channel flows of viscous power-law fluids |
title_fullStr |
Ice shelves as floating channel flows of viscous power-law fluids |
title_full_unstemmed |
Ice shelves as floating channel flows of viscous power-law fluids |
title_sort |
ice shelves as floating channel flows of viscous power-law fluids |
publishDate |
2016 |
url |
https://risweb.st-andrews.ac.uk/portal/en/researchoutput/ice-shelves-as-floating-channel-flows-of-viscous-powerlaw-fluids(a3786a15-c3a6-455e-b8cd-7035ded51c31).html https://doi.org/10.4172/2572-3103.1000150 https://research-repository.st-andrews.ac.uk/bitstream/10023/10134/1/Banik_2016_JOMR_IceShelves_CC.pdf https://arxiv.org/abs/1310.7998 https://www.esciencecentral.org/peer-reviewed/ice-shelves-as-floating-channel-flows-of-viscous-powerlaw-fluids-83254.html |
genre |
Ice Shelf Ice Shelves |
genre_facet |
Ice Shelf Ice Shelves |
op_source |
Banik , I & Dauparas , J 2016 , ' Ice shelves as floating channel flows of viscous power-law fluids ' , Journal of Oceanography and Marine Research , vol. 4 , no. 2 , 150 . https://doi.org/10.4172/2572-3103.1000150 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.4172/2572-3103.1000150 |
container_title |
Journal of Oceanography and Marine Research |
container_volume |
04 |
container_issue |
02 |
_version_ |
1766032398489747456 |