Transitional Flow Dynamics Past a Passively Flapping Airfoil in Gusty Flow

Chandan Bose*, Sayan Gupta, Sunetra Sarkar

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract / Description of output

This paper investigates the transitional flow dynamics behind a passively flapping airfoil supported by nonlinear springs in the presence of gusty inflow. The fluid-structure interaction (FSI) framework is composed of an incompressible Navier-Stokes solver weakly coupled with a two degree-of-freedom (dof) nonlinear structural model. The fluid-elastic system shows a rich bifurcation behavior in terms of successive Hopf bifurcations in uniform flow condition as the mean wind speed is increased. Presence of gusty fluctuations in the inflow makes the dynamics more complex through transitional states that we refer to as ‘intermittency’ between different dynamical states. A regular intermittent state between quasi-periodic dynamics and low amplitude aperiodic response has been observed when the FSI system is subjected to a time harmonic gust in terms of sinusoidal fluctuation. A parametric study has been carried out for various amplitudes and frequencies of the sinusoidal fluctuation to demarcate the transitional regimes. Thereafter, the system is subjected to random gusts modeled as Ornstein-Uhlenbeck process and ‘on-off’ and ‘burst’ type intermittent dynamics have been observed for long time-scale and short time-scale input fluctuations respectively. The intermittent states have been characterized through time series analyses tools and the corresponding flow-field dynamics has been investigated in detail.

Original languageEnglish
Title of host publicationAdvances in Critical Flow Dynamics Involving Moving/Deformable Structures with Design Applications
Subtitle of host publicationProceedings of the IUTAM Symposium on Critical Flow Dynamics involving Moving/Deformable Structures with Design applications, June 18-22, 2018, Santorini, Greece
PublisherSpringer Science and Business Media Deutschland GmbH
Pages135-148
Number of pages14
ISBN (Electronic)978-3-030-55594-8
ISBN (Print)978-3-030-55593-1, 978-3-030-55596-2
DOIs
Publication statusPublished - 11 Feb 2021

Publication series

NameNotes on Numerical Fluid Mechanics and Multidisciplinary Design
Volume147
ISSN (Print)1612-2909
ISSN (Electronic)1860-0824

Keywords / Materials (for Non-textual outputs)

  • Fluid-structure interactions
  • Intermittent flow-field
  • On-off intermittency
  • Ornstein-uhlenbeck process
  • Passive flapping
  • Time harmonic gust

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