Airflow reversal and alternating corkscrew vortices in foredune wake zones during perpendicular and oblique offshore winds

D.W.T. Jackson, M. Beyers, I. Delgado-Fernandez, A.C.W. Baas, Andrew Cooper, K. Lynch

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

On all sandy coastlines fringed by dunes, understanding localised air flow allows us to examine the potential sand transfer between the beach and dunes by wind-blown (Aeolian) action. Traditional thinking into this phenomenon had previously included only onshore winds as effective drivers of this transfer. Recent research by the authors, however, has shown that offshore air-flow too can contribute significantly, through lee-side back eddies, to the overall windblown sediment budget to coastal dunes. Under rising sea levels and increased erosion scenarios, this is an important process in any post-storm recovery of sandy beaches. Until now though, full visualisation in 3D of this newly recognised mechanism in offshore flows has not been achieved. Here we show for the first time this return flow eddy system, using 3D Computational Fluid Dynamics modelling, and reveal the presence of complex corkscrew vortices and other phenomena. The work highlights the importance of relatively small surface undulations in the dune crest which act to induce the spatial patterns of airflow (and transport) found on the adjacent beach.
LanguageEnglish
Pages86-93
JournalGeomorphology
Volume187
DOIs
Publication statusPublished - 3 Mar 2013

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airflow
vortex
dune
beach
eddy
sediment budget
computational fluid dynamics
visualization
erosion
sand
coast
modeling

Keywords

  • Computational Fluid Dynamics
  • aeolian
  • foredunes
  • transport
  • airflow modelling
  • lee side eddies

Cite this

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title = "Airflow reversal and alternating corkscrew vortices in foredune wake zones during perpendicular and oblique offshore winds",
abstract = "On all sandy coastlines fringed by dunes, understanding localised air flow allows us to examine the potential sand transfer between the beach and dunes by wind-blown (Aeolian) action. Traditional thinking into this phenomenon had previously included only onshore winds as effective drivers of this transfer. Recent research by the authors, however, has shown that offshore air-flow too can contribute significantly, through lee-side back eddies, to the overall windblown sediment budget to coastal dunes. Under rising sea levels and increased erosion scenarios, this is an important process in any post-storm recovery of sandy beaches. Until now though, full visualisation in 3D of this newly recognised mechanism in offshore flows has not been achieved. Here we show for the first time this return flow eddy system, using 3D Computational Fluid Dynamics modelling, and reveal the presence of complex corkscrew vortices and other phenomena. The work highlights the importance of relatively small surface undulations in the dune crest which act to induce the spatial patterns of airflow (and transport) found on the adjacent beach.",
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Airflow reversal and alternating corkscrew vortices in foredune wake zones during perpendicular and oblique offshore winds. / Jackson, D.W.T.; Beyers, M.; Delgado-Fernandez, I.; Baas, A.C.W.; Cooper, Andrew; Lynch, K.

In: Geomorphology, Vol. 187, 03.03.2013, p. 86-93.

Research output: Contribution to journalArticle

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AU - Cooper, Andrew

AU - Lynch, K.

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AB - On all sandy coastlines fringed by dunes, understanding localised air flow allows us to examine the potential sand transfer between the beach and dunes by wind-blown (Aeolian) action. Traditional thinking into this phenomenon had previously included only onshore winds as effective drivers of this transfer. Recent research by the authors, however, has shown that offshore air-flow too can contribute significantly, through lee-side back eddies, to the overall windblown sediment budget to coastal dunes. Under rising sea levels and increased erosion scenarios, this is an important process in any post-storm recovery of sandy beaches. Until now though, full visualisation in 3D of this newly recognised mechanism in offshore flows has not been achieved. Here we show for the first time this return flow eddy system, using 3D Computational Fluid Dynamics modelling, and reveal the presence of complex corkscrew vortices and other phenomena. The work highlights the importance of relatively small surface undulations in the dune crest which act to induce the spatial patterns of airflow (and transport) found on the adjacent beach.

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