Controls on Yardang Development and Morphology: 2. Numerical Modeling
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Pelletier-2018-Journal_of_Geop ...
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Pelletier, Jon D.Affiliation
Univ Arizona, Dept GeosciIssue Date
2018-04
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AMER GEOPHYSICAL UNIONCitation
Pelletier, J. D. (2018). Controls on yardang development and morphology: 2. Numerical modeling. Journal of Geophysical Research: Earth Surface, 123, 723–743. https://doi.org/10.1002/2017JF004462Rights
©2018. American Geophysical Union. All Rights Reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
Here I present a set of mathematical modeling results, constrained by the results of the companion paper, aimed at improving our understanding of yardang development and controls on yardang morphology. The classic model for yardang development posits that yardangs evolve to an aspect ratio of approximate to 4 in order to minimize aerodynamic drag. Computational fluid dynamics model results presented here, however, demonstrate that yardangs with an aspect ratio of 4 do not minimize drag. As an alternative, I propose that yardang aspect ratios are primarily controlled by the lateral downwind expansion of wind and wind-blown sediments focused into the troughs among yardangs, which can be quantified using previous studies of wall-bounded turbulent jets. This approach predicts yardangs with aspect ratios in the range of 5 to 10, that is, similar to those of natural yardangs. In addition to aerodynamics, yardang aspect ratios are influenced by the strikes and dips of strata, as demonstrated in the companion paper. To better understand the aerodynamic and bedrock structural controls on yardang morphology, I developed a landscape evolution model that combines the physics of boundary layer flow and abrasion by eolian sediment transport with a model for the erosion of the tops and lee sides of yardangs by water-driven erosional processes. Yardang formation in the model is enhanced in substrates with greater heterogeneity (i.e., alternating strong and weak strata). Yardang morphology is controlled by the strikes and dips of strata as well as the topographic diffusivity associated with water-driven erosional processes.Note
6 month embargo; published online: 02 April 2018ISSN
2169-9003Version
Final published versionSponsors
NSF [1323148]Additional Links
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017JF004462ae974a485f413a2113503eed53cd6c53
10.1002/2017JF004462