Full metadata
Title
Gnamma pit growth and paleowind intensity in the Sonoran Desert: insights from wind tunnel experiments and numerical modeling
Description
Gnamma pit is an Australian aboriginal term for weathering pit. A mix of weathering and aeolian processes controls the formation of gnamma pits. There is a potential to utilize gnamma as an indicator of paleowind intensity because gnamma growth is promoted by the removal of particles from gnamma pits by wind, a process referred to as deflation. Wind tunnel tests determining the wind velocity threshold of deflation over a range of pit dimensions and particles sizes are conducted. Computational fluid dynamics (CFD) modeling utilizing the Re-Normalisation Group (RNG) K-Epsilon turbulence closure is used to investigate the distribution of wall shear stress and turbulent kinetic energy. An empirical equation is proposed to estimate shear stress as a function of the wind velocity and pit depth dimensions. With this equation and Shields Diagram, the wind velocity threshold for evacuating particles in the pit can be estimated by measuring the pit depth ratio and particle size. It is expected that the pit would continue to grow until this threshold is reached. The wind speed deflation threshold is smaller in the wind tunnel than predicted by the CFD and Shields diagram model. This discrepancy may be explained by the large turbulent kinetic energy in the gnamma pit as predicted by the CFD model as compared to the flat bed experiments used to define the Shields diagram. An empirical regression equation of the wind tunnel data is developed to estimate paleowind maximums.
Date Created
2015
Contributors
- Wang, Yinlue (Author)
- Schmeeckle, Mark W (Thesis advisor)
- Dorn, Ronald I. (Committee member)
- Balling, Robert C. (Committee member)
- Arizona State University (Publisher)
Topical Subject
Resource Type
Extent
iv, 51 pages : illustrations (mostly color)
Language
Copyright Statement
In Copyright
Primary Member of
Peer-reviewed
No
Open Access
No
Handle
https://hdl.handle.net/2286/R.I.29908
Statement of Responsibility
by Yinlue Wang
Description Source
Retrieved on Aug. 5, 2015
Level of coding
full
Note
Partial requirement for: M.A., Arizona State University, 2015
Note type
thesis
Includes bibliographical references (pages 24-26)
Note type
bibliography
Field of study: Geography
System Created
- 2015-06-01 08:12:54
System Modified
- 2021-08-30 01:28:57
- 2 years 8 months ago
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