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Fluid-Structure Interactions of Inverted Leaves and Flags


Fan, Boyu (2015) Fluid-Structure Interactions of Inverted Leaves and Flags. Senior thesis (Major), California Institute of Technology. doi:10.7907/Z9GQ6VPC.


Interactions between fluid flows and elastic bodies are ubiquitous in nature. One such phenomena that is encountered on a daily basis is the flapping and fluttering of leaves in the wind. The fluid-structure interaction that governs the physics of a leaf in the wind is poorly understood at best and has potential applications in biomechanics, vehicle design, and energy conversion. We build upon previous work on the flapping dynamics of inverted flags, which are cantilevered elastic sheets with free leading edge and fixed trailing edge that display unique large amplitude oscillatory behaviors. We model a leaf in the laboratory using modified inverted flags, experimentally probing the governing parameters behind leaf fluttering as well as shedding light on the physics behind the inverted flag phenomena. The behavior of these "inverted leaves" studied here display sensitive dependence on two biomechanically relevant parameters, stem-to-leaf rigidity and stem-to-leaf length. In addition, leaves on a tree are not often found alone. We seek to understand the complex interactions of multiple fluttering and flapping leaves by way of examining the interactions between pairs of inverted flags. Coupling through their flow fields, pairs of inverted flags exhibit striking emergent phenomena. We report these observed dynamical behaviors and the conditions upon which they arise.

Item Type:Thesis (Senior thesis (Major))
Subject Keywords:fluid-structure interaction, flapping flags, aerodynamics
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Awards:Library Friends Senior Thesis Prize Finalist, 2015. George W. And Bernice E. Green Memorial Prize, 2015.
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Gharib, Morteza
Group:Senior Undergraduate Thesis Prize
Thesis Committee:
  • None, None
Defense Date:5 June 2015
Non-Caltech Author Email:bfan17 (AT)
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Lester Lees Aeronautics Summer Undergraduate Research FellowshipUNSPECIFIED
Record Number:CaltechTHESIS:10272015-171407458
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9252
Deposited By: Boyu Fan
Deposited On:29 Oct 2015 23:02
Last Modified:09 Aug 2022 16:58

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