Blade dynamics in combined waves and current
Name
BladeDynamicsCombinedWC_2nd revision.pdf
Description
Accepted version
Size
1.13 MB
Format
Adobe PDF
Checksum (MD5)
eb15c77148b88f14f9bbdad96502944a
Author(s)
Lei, Jiarui
Nepf, Heidi
Date Issued
May 2019
Journal
Journal of Fluids and Structures
Publisher
Elsevier BV
Citation
Lei, Jiarui and Heidi Nepf. "Blade dynamics in combined waves and current." Journal of Fluids and Structures 87 (May 2019): 137-149 © 2019 Elsevier Ltd
Version
Author's final manuscript
Abstract
Submerged aquatic vegetation (SAV), such as seagrass, is flexible and reconfigures (bends) in response to waves and current. The blade motion and reconfiguration modify the hydrodynamic drag. The modified drag can be described by an effective blade length, l e , which is defined as the length of a rigid blade that results in the same drag as a flexible blade of length l. In many natural settings SAV is exposed to combinations of waves and current. This study derived and used laboratory measurements to validate new predictions of effective blade length for combined waves and current based on a Cauchy number, which describes the ratio of hydrodynamic drag to the restoring force due to rigidity of blade. Force measurements on and digital images of blades exposed to waves with a 2-s period and with a range of wave velocity (U w ) and current speed (U c ) were used to estimate the effective blade length. The measurements were also used to validate a numerical simulation of blade motion. Once validated, the simulation was used to expand the investigated parameter space to a wider range of wave conditions, and in particular longer wave periods. ForU c <[Formula presented]U w , the blade motion and hydrodynamic drag were wave-dominated. For U c >2U w , the blade motion and hydrodynamic drag were current-dominated.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Terms of Use
Creative Commons Attribution-NonCommercial-NoDerivs License
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1016/j.jfluidstructs.2019.03.020
