Journal of the Korean Society of Visualization (한국가시화정보학회지)

The Korean Society of Visualization (한국가시화정보학회)
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Fluttering Characteristics of Free-falling Plates

자유낙하하는 판의 fluttering 특성 연구

  • Hong, Seulki (Department of Mechanical Engineering, Ulsan National Institute of Science and Technology) ;
  • Chae, Seokbong (Department of Mechanical Engineering, Ulsan National Institute of Science and Technology) ;
  • Kim, Jooha (Department of Mechanical Engineering, Ulsan National Institute of Science and Technology)
  • Received : 2017.07.29
  • Accepted : 2017.08.26
  • Published : 2017.08.31
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Abstract

Abstract In the present study, the characteristics of kinematics and dynamics in the fluttering motion of free-falling plates are investigated at Reynolds number of $10^5$. We record quasi-two-dimensional trajectories of free-falling plates with and without superhydrophobic coating using high-speed camera, and compute the drag and lift forces by trajectory analysis. Translational and angular velocities are modeled as harmonic functions with specific phase differences. In particular, periodic mass elevations near turning points are explained using the suggested models. At each turning point, a sudden drop in lift and a rapid increase in drag occur simultaneously due to fast increase in angle of attack. However, the lift is increased over the buoyancy-corrected weight of plate during gliding flight, resulting in periodic mass elevations near turning points. Superhydrophobicity is shown to increase lift but to reduce drag on a fluttering plate, resulting in the decrease of mean descent speed.

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References

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