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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Published in:Physical Review Fluids
Main Authors: Howland (Christopher J. ), Roberto Verzicco, Detlef Lohse
Other Authors: Howland (Christopher, J), Verzicco, R, Lohse, D
Format: Article in Journal/Newspaper
Language:English
Published: American Physical Society 2023
Subjects:
Online Access:https://hdl.handle.net/2108/361709
https://doi.org/10.1103/PhysRevFluids.8.013501
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spelling ftunivromatorver:oai:art.torvergata.it:2108/361709 2024-06-09T07:46:52+00:00 Double-diffusive transport in multicomponent vertical convection Howland (Christopher J. ) Roberto Verzicco Detlef Lohse Howland (Christopher, J) Verzicco, R Lohse, D 2023 https://hdl.handle.net/2108/361709 https://doi.org/10.1103/PhysRevFluids.8.013501 eng eng American Physical Society country:US volume:8 issue:1 journal:PHYSICAL REVIEW FLUIDS https://hdl.handle.net/2108/361709 doi:10.1103/PhysRevFluids.8.013501 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85146368499 Settore ING-IND/06 info:eu-repo/semantics/article 2023 ftunivromatorver https://doi.org/10.1103/PhysRevFluids.8.013501 2024-05-14T23:37:46Z 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≈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≈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 Universitá degli Studi di Roma "Tor Vergata": ART - Archivio Istituzionale della Ricerca Physical Review Fluids 8 1
institution Open Polar
collection Universitá degli Studi di Roma "Tor Vergata": ART - Archivio Istituzionale della Ricerca
op_collection_id ftunivromatorver
language English
topic Settore ING-IND/06
spellingShingle Settore ING-IND/06
Howland (Christopher J. )
Roberto Verzicco
Detlef Lohse
Double-diffusive transport in multicomponent vertical convection
topic_facet Settore ING-IND/06
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≈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≈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.
author2 Howland (Christopher, J)
Verzicco, R
Lohse, D
format Article in Journal/Newspaper
author Howland (Christopher J. )
Roberto Verzicco
Detlef Lohse
author_facet Howland (Christopher J. )
Roberto Verzicco
Detlef Lohse
author_sort Howland (Christopher J. )
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
publisher American Physical Society
publishDate 2023
url https://hdl.handle.net/2108/361709
https://doi.org/10.1103/PhysRevFluids.8.013501
genre Ice Shelves
genre_facet Ice Shelves
op_relation volume:8
issue:1
journal:PHYSICAL REVIEW FLUIDS
https://hdl.handle.net/2108/361709
doi:10.1103/PhysRevFluids.8.013501
info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85146368499
op_doi https://doi.org/10.1103/PhysRevFluids.8.013501
container_title Physical Review Fluids
container_volume 8
container_issue 1
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