Double-diffusive transport in multicomponent vertical convection
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 sali...
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ftpubman:oai:pure.mpg.de:item_3513903 2023-08-27T04:10:04+02:00 Double-diffusive transport in multicomponent vertical convection Howland, C. Verzicco, R. Lohse, D. 2023 application/pdf http://hdl.handle.net/21.11116/0000-000D-44C1-C http://hdl.handle.net/21.11116/0000-000D-44C3-A eng eng info:eu-repo/grantAgreement/EC/H2020/804283 info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevFluids.8.013501 http://hdl.handle.net/21.11116/0000-000D-44C1-C http://hdl.handle.net/21.11116/0000-000D-44C3-A Physical Review Fluids info:eu-repo/semantics/article 2023 ftpubman https://doi.org/10.1103/PhysRevFluids.8.013501 2023-08-02T01:56:41Z 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 find that the heat transport is determined by a turbulent Prandtl number of Prt approximate to 1 and that double-diffusive effects are practically negligible. However, the difference in molecular diffusivities plays an important role close to the boundaries. In the (unrealistic) case where salt diffused faster than heat, the ratio of salt-to-heat fluxes would scale as Le1/3, consistent with classical nested scalar boundary layers. However, in the realistic case of faster heat diffusion (relative to salt), we observe a transition towards a Le1/2 scaling of the ratio of the fluxes. This coincides with the thermal boundary layer width growing beyond the thickness of the viscous boundary layer. We find that this transition is not determined by a critical Lewis number, but rather by a critical Prandtl number Pr approximate to 10, slightly below that for cold seawater where Pr = 14. We compare our results to similar studies of sheared and double-diffusive flow under ice shelves, and discuss the implications for fluxes in large-scale ice-ocean models. By coupling our results to ice-ocean interface thermodynamics, we describe how the flux ratio impacts the interfacial salinity, and hence the strength of solutal convection and the ablation rate. Article in Journal/Newspaper Ice Shelves Max Planck Society: MPG.PuRe Physical Review Fluids 8 1 |
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Max Planck Society: MPG.PuRe |
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ftpubman |
language |
English |
description |
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 find that the heat transport is determined by a turbulent Prandtl number of Prt approximate to 1 and that double-diffusive effects are practically negligible. However, the difference in molecular diffusivities plays an important role close to the boundaries. In the (unrealistic) case where salt diffused faster than heat, the ratio of salt-to-heat fluxes would scale as Le1/3, consistent with classical nested scalar boundary layers. However, in the realistic case of faster heat diffusion (relative to salt), we observe a transition towards a Le1/2 scaling of the ratio of the fluxes. This coincides with the thermal boundary layer width growing beyond the thickness of the viscous boundary layer. We find that this transition is not determined by a critical Lewis number, but rather by a critical Prandtl number Pr approximate to 10, slightly below that for cold seawater where Pr = 14. We compare our results to similar studies of sheared and double-diffusive flow under ice shelves, and discuss the implications for fluxes in large-scale ice-ocean models. By coupling our results to ice-ocean interface thermodynamics, we describe how the flux ratio impacts the interfacial salinity, and hence the strength of solutal convection and the ablation rate. |
format |
Article in Journal/Newspaper |
author |
Howland, C. Verzicco, R. Lohse, D. |
spellingShingle |
Howland, C. Verzicco, R. Lohse, D. Double-diffusive transport in multicomponent vertical convection |
author_facet |
Howland, C. Verzicco, R. Lohse, D. |
author_sort |
Howland, C. |
title |
Double-diffusive transport in multicomponent vertical convection |
title_short |
Double-diffusive transport in multicomponent vertical convection |
title_full |
Double-diffusive transport in multicomponent vertical convection |
title_fullStr |
Double-diffusive transport in multicomponent vertical convection |
title_full_unstemmed |
Double-diffusive transport in multicomponent vertical convection |
title_sort |
double-diffusive transport in multicomponent vertical convection |
publishDate |
2023 |
url |
http://hdl.handle.net/21.11116/0000-000D-44C1-C http://hdl.handle.net/21.11116/0000-000D-44C3-A |
genre |
Ice Shelves |
genre_facet |
Ice Shelves |
op_source |
Physical Review Fluids |
op_relation |
info:eu-repo/grantAgreement/EC/H2020/804283 info:eu-repo/semantics/altIdentifier/doi/10.1103/PhysRevFluids.8.013501 http://hdl.handle.net/21.11116/0000-000D-44C1-C http://hdl.handle.net/21.11116/0000-000D-44C3-A |
op_doi |
https://doi.org/10.1103/PhysRevFluids.8.013501 |
container_title |
Physical Review Fluids |
container_volume |
8 |
container_issue |
1 |
_version_ |
1775351827777191936 |