Gradient -diffusion closure and the ejection -sweep cycle in convective boundary layers
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| Format: | Artículo científico |
| Language: | en |
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Universidade Federal de Santa Maria
2016
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| _version_ | 1876436483247702016 |
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| author | Khaled Ghannam |
| author_facet | Khaled Ghannam |
| contents | Gradient -diffusion closure and the ejection -sweep cycle in convective boundary layers Khaled Ghannam Tomer Duman Gabriel G. Katul Marcelo Chamecki Estudios Ambientales second ejection sweep cycle order closure Convective boundary layer The inadequacy of conventional gradient -diffusion closure in modeling turbulent heat flux within the convective atmosphe ric boundary -layer is often alleviated by accounting for nonlocal transport. Such nonlocal effects are a manifestation of the inherent asy mmetry in vertical transport in the convective boundary layer, which is in turn associated with third -order moments (s kewness and fluxes of fluxes). In this work, the role of these third -order moments in second -order turbulence closure of the sensible heat flux is examined with the goal of reconciling the models to various closure assumptions . S urface layer similarity the ory and mixed -layer parametrizations are used here, complemented by LES results when needed. The turbulent heat flux with various closure assumptions of the flux transport term ( ) is solved, including both local and nonlocal approaches. We con nect to ejection -sweep cycle s in the flow field using the Gram - Charlier cumulant expansion of the joint probability distribution of vertical velocity and potential temperature . In this nonlocal closure, the transport asymmetry models that include the vertical velocity skewness as a correction term to H originate from ejection -sweep events. Vertical inhomogeneity results in a modified -skewness correction to the nonlocal contribution to the heat flux associated with the relative intensity of ejections a nd sweeps . 2016 artículo científico 0100-8307 https://www.redalyc.org/articulo.oa?id=467547689089 en http://www.redalyc.org/revista.oa?id=4675 Ciência e Natura application/pdf Universidade Federal de Santa Maria Ciência e Natura (Brasil) Vol.38 |
| format | Artículo científico |
| id | redalyc_467547689089 |
| institution | Redalyc |
| language | en |
| publishDate | 2016 |
| publisher | Universidade Federal de Santa Maria |
| spellingShingle | Gradient -diffusion closure and the ejection -sweep cycle in convective boundary layers Khaled Ghannam Estudios Ambientales second ejection sweep cycle order closure Convective boundary layer Gradient -diffusion closure and the ejection -sweep cycle in convective boundary layers Khaled Ghannam Tomer Duman Gabriel G. Katul Marcelo Chamecki Estudios Ambientales second ejection sweep cycle order closure Convective boundary layer The inadequacy of conventional gradient -diffusion closure in modeling turbulent heat flux within the convective atmosphe ric boundary -layer is often alleviated by accounting for nonlocal transport. Such nonlocal effects are a manifestation of the inherent asy mmetry in vertical transport in the convective boundary layer, which is in turn associated with third -order moments (s kewness and fluxes of fluxes). In this work, the role of these third -order moments in second -order turbulence closure of the sensible heat flux is examined with the goal of reconciling the models to various closure assumptions . S urface layer similarity the ory and mixed -layer parametrizations are used here, complemented by LES results when needed. The turbulent heat flux with various closure assumptions of the flux transport term ( ) is solved, including both local and nonlocal approaches. We con nect to ejection -sweep cycle s in the flow field using the Gram - Charlier cumulant expansion of the joint probability distribution of vertical velocity and potential temperature . In this nonlocal closure, the transport asymmetry models that include the vertical velocity skewness as a correction term to H originate from ejection -sweep events. Vertical inhomogeneity results in a modified -skewness correction to the nonlocal contribution to the heat flux associated with the relative intensity of ejections a nd sweeps . 2016 artículo científico 0100-8307 https://www.redalyc.org/articulo.oa?id=467547689089 en http://www.redalyc.org/revista.oa?id=4675 Ciência e Natura application/pdf Universidade Federal de Santa Maria Ciência e Natura (Brasil) Vol.38 |
| title | Gradient -diffusion closure and the ejection -sweep cycle in convective boundary layers |
| topic | Estudios Ambientales second ejection sweep cycle order closure Convective boundary layer |
| url | https://www.redalyc.org/articulo.oa?id=467547689089 |