Three dimensional airflow patterns within a coastal trough–bowl blowout during fresh breeze to hurricane force winds

Thomas Smyth, Derek Jackson, Andrew Cooper

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Wind flow within blowouts is extremely complex as streamline compression, expansion and reversal may occur over and around a single landform. As a result high resolution temporal and spatial measurements are required during a range of incident wind conditions to resolve near surface airflow patterns and turbulent structures. This study examined three-dimensional airflow within a coastal dune trough–bowl blowout using 15 ultrasonic anemometers (UAs) and a high resolution computational fluid dynamics model.

Measured total wind speed and vertical wind speed behaved consistently through 5 Beaufort wind scales ranging from ‘fresh breeze’ to ‘strong gale’, increasing relative to incident wind speed, whilst wind direction at each UA did not alter. Due to the agreement of modelled and measured data, ‘hurricane’ (37 m s−1) incident winds were also simulated and were consistent with modelled and measured wind direction at lower wind speeds. Modelled wind turbulence data was not compared with measured as only average conditions were simulated. However, the standard deviation of measured wind direction remained constant at each anemometer throughout the range of incident wind speeds, whilst the standard deviation of wind speed and turbulent kinetic energy increased relative to incident wind speed.

This paper demonstrates that wind flow behaviour within blowouts throughout this range of wind speeds is governed by topography and is relative to, but does not change structurally with incident wind speed. As a result the extent of streamline compression, expansion, steering and reversal remain constant.
LanguageEnglish
Pages111-123
Number of pages13
JournalAeolian Research
Volume9
Early online date11 Apr 2013
DOIs
Publication statusPublished - 1 Jun 2013
Externally publishedYes

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blowout
hurricane
airflow
trough
wind velocity
anemometer
wind direction
compression
computational fluid dynamics
kinetic energy
landform
dune
turbulence
topography

Cite this

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abstract = "Wind flow within blowouts is extremely complex as streamline compression, expansion and reversal may occur over and around a single landform. As a result high resolution temporal and spatial measurements are required during a range of incident wind conditions to resolve near surface airflow patterns and turbulent structures. This study examined three-dimensional airflow within a coastal dune trough–bowl blowout using 15 ultrasonic anemometers (UAs) and a high resolution computational fluid dynamics model.Measured total wind speed and vertical wind speed behaved consistently through 5 Beaufort wind scales ranging from ‘fresh breeze’ to ‘strong gale’, increasing relative to incident wind speed, whilst wind direction at each UA did not alter. Due to the agreement of modelled and measured data, ‘hurricane’ (37 m s−1) incident winds were also simulated and were consistent with modelled and measured wind direction at lower wind speeds. Modelled wind turbulence data was not compared with measured as only average conditions were simulated. However, the standard deviation of measured wind direction remained constant at each anemometer throughout the range of incident wind speeds, whilst the standard deviation of wind speed and turbulent kinetic energy increased relative to incident wind speed.This paper demonstrates that wind flow behaviour within blowouts throughout this range of wind speeds is governed by topography and is relative to, but does not change structurally with incident wind speed. As a result the extent of streamline compression, expansion, steering and reversal remain constant.",
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Three dimensional airflow patterns within a coastal trough–bowl blowout during fresh breeze to hurricane force winds. / Smyth, Thomas; Jackson, Derek ; Cooper, Andrew.

In: Aeolian Research, Vol. 9, 01.06.2013, p. 111-123.

Research output: Contribution to journalArticle

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