Effect of an orientation-dependent non-linear grain fluidity on bulk directional enhancement factors
Bulk directional enhancement factors are determined for axisymmetric (girdle and single-maximum) orientation fabrics using a transversely isotropic grain rheology with an orientation-dependent non-linear grain fluidity. Compared to grain fluidities that are simplified as orientation independent, we...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Cambridge University Press
2021-06-01
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| Series: | Journal of Glaciology |
| Subjects: | |
| Online Access: | https://www.cambridge.org/core/product/identifier/S0022143020001173/type/journal_article |
| _version_ | 1811155817205858304 |
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| author | Nicholas M. Rathmann Christine S. Hvidberg Aslak Grinsted David A. Lilien Dorthe Dahl-Jensen |
| author_facet | Nicholas M. Rathmann Christine S. Hvidberg Aslak Grinsted David A. Lilien Dorthe Dahl-Jensen |
| author_sort | Nicholas M. Rathmann |
| collection | DOAJ |
| description | Bulk directional enhancement factors are determined for axisymmetric (girdle and single-maximum) orientation fabrics using a transversely isotropic grain rheology with an orientation-dependent non-linear grain fluidity. Compared to grain fluidities that are simplified as orientation independent, we find that bulk strain-rate enhancements for intermediate-to-strong axisymmetric fabrics can be up to a factor of ten larger, assuming stress homogenization over the polycrystal scale. Our work thus extends previous results based on simple basal slip (Schmid) grain rheologies to the transversely isotropic rheology, which has implications for large-scale anisotropic ice-flow modelling that relies on a transversely isotropic grain rheology. In order to derive bulk enhancement factors for arbitrary evolving fabrics, we expand the c-axis distribution in terms of a spherical harmonic series, which allows the rheology-required structure tensors through order eight to easily be calculated and provides an alternative to current structure-tensor-based modelling. |
| first_indexed | 2024-04-10T04:39:57Z |
| format | Article |
| id | doaj.art-b4fe359c86e147459c8960807867537a |
| institution | Directory Open Access Journal |
| issn | 0022-1430 1727-5652 |
| language | English |
| last_indexed | 2024-04-10T04:39:57Z |
| publishDate | 2021-06-01 |
| publisher | Cambridge University Press |
| record_format | Article |
| series | Journal of Glaciology |
| spelling | doaj.art-b4fe359c86e147459c8960807867537a2023-03-09T12:41:06ZengCambridge University PressJournal of Glaciology0022-14301727-56522021-06-016756957510.1017/jog.2020.117Effect of an orientation-dependent non-linear grain fluidity on bulk directional enhancement factorsNicholas M. Rathmann0https://orcid.org/0000-0001-7140-0931Christine S. Hvidberg1Aslak Grinsted2David A. Lilien3https://orcid.org/0000-0001-8667-8020Dorthe Dahl-Jensen4https://orcid.org/0000-0002-1474-1948Niels Bohr Institute, University of Copenhagen, Copenhagen, DenmarkNiels Bohr Institute, University of Copenhagen, Copenhagen, DenmarkNiels Bohr Institute, University of Copenhagen, Copenhagen, DenmarkNiels Bohr Institute, University of Copenhagen, Copenhagen, DenmarkNiels Bohr Institute, University of Copenhagen, Copenhagen, DenmarkBulk directional enhancement factors are determined for axisymmetric (girdle and single-maximum) orientation fabrics using a transversely isotropic grain rheology with an orientation-dependent non-linear grain fluidity. Compared to grain fluidities that are simplified as orientation independent, we find that bulk strain-rate enhancements for intermediate-to-strong axisymmetric fabrics can be up to a factor of ten larger, assuming stress homogenization over the polycrystal scale. Our work thus extends previous results based on simple basal slip (Schmid) grain rheologies to the transversely isotropic rheology, which has implications for large-scale anisotropic ice-flow modelling that relies on a transversely isotropic grain rheology. In order to derive bulk enhancement factors for arbitrary evolving fabrics, we expand the c-axis distribution in terms of a spherical harmonic series, which allows the rheology-required structure tensors through order eight to easily be calculated and provides an alternative to current structure-tensor-based modelling.https://www.cambridge.org/core/product/identifier/S0022143020001173/type/journal_articleAnisotropic iceice rheologyice-sheet modelling |
| spellingShingle | Nicholas M. Rathmann Christine S. Hvidberg Aslak Grinsted David A. Lilien Dorthe Dahl-Jensen Effect of an orientation-dependent non-linear grain fluidity on bulk directional enhancement factors Journal of Glaciology Anisotropic ice ice rheology ice-sheet modelling |
| title | Effect of an orientation-dependent non-linear grain fluidity on bulk directional enhancement factors |
| title_full | Effect of an orientation-dependent non-linear grain fluidity on bulk directional enhancement factors |
| title_fullStr | Effect of an orientation-dependent non-linear grain fluidity on bulk directional enhancement factors |
| title_full_unstemmed | Effect of an orientation-dependent non-linear grain fluidity on bulk directional enhancement factors |
| title_short | Effect of an orientation-dependent non-linear grain fluidity on bulk directional enhancement factors |
| title_sort | effect of an orientation dependent non linear grain fluidity on bulk directional enhancement factors |
| topic | Anisotropic ice ice rheology ice-sheet modelling |
| url | https://www.cambridge.org/core/product/identifier/S0022143020001173/type/journal_article |
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