Large Eddy Simulation of an Inhomogeneous Atmospheric Boundary Layer under Neutral Conditions.
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| Title: | Large Eddy Simulation of an Inhomogeneous Atmospheric Boundary Layer under Neutral Conditions. |
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| Authors: | Lin, Ching-Long, Glendening, John W. |
| Source: | Journal of the Atmospheric Sciences. 8/15/2002, Vol. 59 Issue 16, p2479. 19p. |
| Subjects: | Atmospheric boundary layer, Surface roughness, Vortex motion |
| Abstract: | Flow structures in an inhomogeneous neutrally stratified atmospheric boundary layer flow, obtained from large eddy simulation, are analyzed and compared with homogeneous case counterparts. The inhomogeneity is imposed in the streamwise direction by using two different surface roughness heights z[sub o], each covering a streamwise distance of 4.8 km, to produce internal boundary layers. Adjustments of the mean velocity profiles are primarily confined to the lowest 140 m of the overlying boundary layer, with parcels being accelerated and decelerated over the respective smooth and rough surfaces. For large fetches downwind of the surface roughness discontinuities, the mean velocity profiles close to the surface are approximately logarithmic, but fitting to Monin-Obukhov similarity profiles using the z[sub o] and stress of the underlying surface requires that the von Kármán constant be k = 0.4 over the smooth surface and k = 0.37 over the rough surface. Much of this difference is attributed to velocity accelerations created by locally induced pressure gradient forces within the boundary layer, requiring k to be adjusted when horizontally homogeneous similarity expressions are utilized. Quadrant analysis indicates that ejection and sweep intensities differ from those of homogeneous surface cases but the occurrence frequencies are similar. Budget analysis of momentum flux indicates that the shear production and pressure destruction terms roughly balance, which is consistent with previous homogeneous surface findings. Flow visualization and conditional sampling demonstrate that these two terms are physically associated with ejections, sweeps, and vortical structures. [ABSTRACT FROM AUTHOR] |
| Copyright of Journal of the Atmospheric Sciences is the property of American Meteorological Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Links: – Type: pdflink Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 6933666 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Large Eddy Simulation of an Inhomogeneous Atmospheric Boundary Layer under Neutral Conditions. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Lin%2C+Ching-Long%22">Lin, Ching-Long</searchLink><br /><searchLink fieldCode="AR" term="%22Glendening%2C+John+W%2E%22">Glendening, John W.</searchLink> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Journal+of+the+Atmospheric+Sciences%22">Journal of the Atmospheric Sciences</searchLink>. 8/15/2002, Vol. 59 Issue 16, p2479. 19p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Atmospheric+boundary+layer%22">Atmospheric boundary layer</searchLink><br /><searchLink fieldCode="DE" term="%22Surface+roughness%22">Surface roughness</searchLink><br /><searchLink fieldCode="DE" term="%22Vortex+motion%22">Vortex motion</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Flow structures in an inhomogeneous neutrally stratified atmospheric boundary layer flow, obtained from large eddy simulation, are analyzed and compared with homogeneous case counterparts. The inhomogeneity is imposed in the streamwise direction by using two different surface roughness heights z[sub o], each covering a streamwise distance of 4.8 km, to produce internal boundary layers. Adjustments of the mean velocity profiles are primarily confined to the lowest 140 m of the overlying boundary layer, with parcels being accelerated and decelerated over the respective smooth and rough surfaces. For large fetches downwind of the surface roughness discontinuities, the mean velocity profiles close to the surface are approximately logarithmic, but fitting to Monin-Obukhov similarity profiles using the z[sub o] and stress of the underlying surface requires that the von Kármán constant be k = 0.4 over the smooth surface and k = 0.37 over the rough surface. Much of this difference is attributed to velocity accelerations created by locally induced pressure gradient forces within the boundary layer, requiring k to be adjusted when horizontally homogeneous similarity expressions are utilized. Quadrant analysis indicates that ejection and sweep intensities differ from those of homogeneous surface cases but the occurrence frequencies are similar. Budget analysis of momentum flux indicates that the shear production and pressure destruction terms roughly balance, which is consistent with previous homogeneous surface findings. Flow visualization and conditional sampling demonstrate that these two terms are physically associated with ejections, sweeps, and vortical structures. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Journal of the Atmospheric Sciences is the property of American Meteorological Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1175/1520-0469(2002)059<2479:LESOAI>2.0.CO;2 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 19 StartPage: 2479 Subjects: – SubjectFull: Atmospheric boundary layer Type: general – SubjectFull: Surface roughness Type: general – SubjectFull: Vortex motion Type: general Titles: – TitleFull: Large Eddy Simulation of an Inhomogeneous Atmospheric Boundary Layer under Neutral Conditions. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Lin, Ching-Long – PersonEntity: Name: NameFull: Glendening, John W. IsPartOfRelationships: – BibEntity: Dates: – D: 15 M: 08 Text: 8/15/2002 Type: published Y: 2002 Identifiers: – Type: issn-print Value: 00224928 Numbering: – Type: volume Value: 59 – Type: issue Value: 16 Titles: – TitleFull: Journal of the Atmospheric Sciences Type: main |
| ResultId | 1 |
