Direkte numerische Simulation von Salzfingern = Direct numerical simulation of saltfingers / Thomas Zweigle
The phenomena of double-diffusive processes occur when two fluids with molecular diffusivities, operating on different scales, are combined. This process was recognized first by Arons and Stommel and later described with linear theory by Stern in 1960. A gravitationally stable fluid layer, with a st...
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Alfred Wegener Institute for Polar and Marine Research
2011
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Online Access: | https://epic.awi.de/id/eprint/30017/ https://epic.awi.de/id/eprint/30017/1/635-2011_Zweigle.pdf https://hdl.handle.net/10013/epic.38404 https://hdl.handle.net/10013/epic.38404.d001 |
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ftawi:oai:epic.awi.de:30017 2024-09-09T19:33:25+00:00 Direkte numerische Simulation von Salzfingern = Direct numerical simulation of saltfingers / Thomas Zweigle Zweigle, Thomas 2011 application/pdf https://epic.awi.de/id/eprint/30017/ https://epic.awi.de/id/eprint/30017/1/635-2011_Zweigle.pdf https://hdl.handle.net/10013/epic.38404 https://hdl.handle.net/10013/epic.38404.d001 unknown Alfred Wegener Institute for Polar and Marine Research https://epic.awi.de/id/eprint/30017/1/635-2011_Zweigle.pdf https://hdl.handle.net/10013/epic.38404.d001 Zweigle, T. (2011) Direkte numerische Simulation von Salzfingern = Direct numerical simulation of saltfingers / Thomas Zweigle , Berichte zur Polar- und Meeresforschung (Reports on Polar and Marine Research), Bremerhaven, Alfred Wegener Institute for Polar and Marine Research, 635 , 123 p. . doi:10.2312/BzPM_0635_2011 <https://doi.org/10.2312/BzPM_0635_2011> , hdl:10013/epic.38404 EPIC3Berichte zur Polar- und Meeresforschung (Reports on Polar and Marine Research), Bremerhaven, Alfred Wegener Institute for Polar and Marine Research, 635, 123 p., ISSN: 1866-3192 "Berichte zur Polar- und Meeresforschung" notRev 2011 ftawi https://doi.org/10.2312/BzPM_0635_2011 2024-06-24T04:03:54Z The phenomena of double-diffusive processes occur when two fluids with molecular diffusivities, operating on different scales, are combined. This process was recognized first by Arons and Stommel and later described with linear theory by Stern in 1960. A gravitationally stable fluid layer, with a stabilizing and a destabilizing component, is the initial state for double-diffusive processes. The release of potential energy by Doublediffusion results in destabilization of this layer. Instability develop and produce local fingerlike structures – the so called saltfingers. These lead to large scale convection of temperature and salinity that is direct against the stabilizing gradients. These kind of processes are not limited to ocean circulation only, Double-diffusion is also found in astrophysics (big Helium-stars), the earth core, metal alloy, refilling of gas reservoirs, etc. The main objective of this work is an estimation of the effective diffusivities of temperature and salinity, caused by saltfingering and is realized by means of direct numerical simulation (DNS). These effective diffusivities were used to compare the results with published values and test existing parametrisations. In this way, the effective diffusivity of temperature and salinity could be described by parametrisation. Also, the law of effective diffusivities by Merryfield was in well agreement with the effective fluxes, estimated in the salt-finger simulations of this work. Salt-finger processes were studied in several publications, but, semiconvection in the ocean was never modeled before by direct numerical simulation (DNS). Compared to saltfingering, semiconvection occurs as a process with a much more stable layering – with smaller thermohaline steps (0.5 − 5 m) in contrast to saltfingers (20 − 100 m) – and a narrow parameter range of stability. The developing of effective diffusivity by semiconvetion does not arrive at values of saltfingering. Other/Unknown Material Berichte zur Polar- und Meeresforschung Reports on Polar and Marine Research Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
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ftawi |
language |
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description |
The phenomena of double-diffusive processes occur when two fluids with molecular diffusivities, operating on different scales, are combined. This process was recognized first by Arons and Stommel and later described with linear theory by Stern in 1960. A gravitationally stable fluid layer, with a stabilizing and a destabilizing component, is the initial state for double-diffusive processes. The release of potential energy by Doublediffusion results in destabilization of this layer. Instability develop and produce local fingerlike structures – the so called saltfingers. These lead to large scale convection of temperature and salinity that is direct against the stabilizing gradients. These kind of processes are not limited to ocean circulation only, Double-diffusion is also found in astrophysics (big Helium-stars), the earth core, metal alloy, refilling of gas reservoirs, etc. The main objective of this work is an estimation of the effective diffusivities of temperature and salinity, caused by saltfingering and is realized by means of direct numerical simulation (DNS). These effective diffusivities were used to compare the results with published values and test existing parametrisations. In this way, the effective diffusivity of temperature and salinity could be described by parametrisation. Also, the law of effective diffusivities by Merryfield was in well agreement with the effective fluxes, estimated in the salt-finger simulations of this work. Salt-finger processes were studied in several publications, but, semiconvection in the ocean was never modeled before by direct numerical simulation (DNS). Compared to saltfingering, semiconvection occurs as a process with a much more stable layering – with smaller thermohaline steps (0.5 − 5 m) in contrast to saltfingers (20 − 100 m) – and a narrow parameter range of stability. The developing of effective diffusivity by semiconvetion does not arrive at values of saltfingering. |
format |
Other/Unknown Material |
author |
Zweigle, Thomas |
spellingShingle |
Zweigle, Thomas Direkte numerische Simulation von Salzfingern = Direct numerical simulation of saltfingers / Thomas Zweigle |
author_facet |
Zweigle, Thomas |
author_sort |
Zweigle, Thomas |
title |
Direkte numerische Simulation von Salzfingern = Direct numerical simulation of saltfingers / Thomas Zweigle |
title_short |
Direkte numerische Simulation von Salzfingern = Direct numerical simulation of saltfingers / Thomas Zweigle |
title_full |
Direkte numerische Simulation von Salzfingern = Direct numerical simulation of saltfingers / Thomas Zweigle |
title_fullStr |
Direkte numerische Simulation von Salzfingern = Direct numerical simulation of saltfingers / Thomas Zweigle |
title_full_unstemmed |
Direkte numerische Simulation von Salzfingern = Direct numerical simulation of saltfingers / Thomas Zweigle |
title_sort |
direkte numerische simulation von salzfingern = direct numerical simulation of saltfingers / thomas zweigle |
publisher |
Alfred Wegener Institute for Polar and Marine Research |
publishDate |
2011 |
url |
https://epic.awi.de/id/eprint/30017/ https://epic.awi.de/id/eprint/30017/1/635-2011_Zweigle.pdf https://hdl.handle.net/10013/epic.38404 https://hdl.handle.net/10013/epic.38404.d001 |
genre |
Berichte zur Polar- und Meeresforschung Reports on Polar and Marine Research |
genre_facet |
Berichte zur Polar- und Meeresforschung Reports on Polar and Marine Research |
op_source |
EPIC3Berichte zur Polar- und Meeresforschung (Reports on Polar and Marine Research), Bremerhaven, Alfred Wegener Institute for Polar and Marine Research, 635, 123 p., ISSN: 1866-3192 |
op_relation |
https://epic.awi.de/id/eprint/30017/1/635-2011_Zweigle.pdf https://hdl.handle.net/10013/epic.38404.d001 Zweigle, T. (2011) Direkte numerische Simulation von Salzfingern = Direct numerical simulation of saltfingers / Thomas Zweigle , Berichte zur Polar- und Meeresforschung (Reports on Polar and Marine Research), Bremerhaven, Alfred Wegener Institute for Polar and Marine Research, 635 , 123 p. . doi:10.2312/BzPM_0635_2011 <https://doi.org/10.2312/BzPM_0635_2011> , hdl:10013/epic.38404 |
op_doi |
https://doi.org/10.2312/BzPM_0635_2011 |
_version_ |
1809902868478558208 |