Unsteady Viscous Flow over Elliptic Cylinders at Various Thickness with Different Reynolds Numbers

Kim, Moon-Sang

doi:10.2514/6.2005-5130

Cited by 5 publications

(2 citation statements)

References 18 publications

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“…In previous studies, lift and drag forces have been studied over different cross section shapes like circles [10][11][12][13][14][15], squares [16,17], ellipses [18][19][20] and half-circles [21][22][23][24][25]. We aim to extend the previous research by studying the variation of hydrodynamic forces and vortex shedding frequency as the shape of the body changes from a circular cylinder to a more streamlined or a more bluff body.…”

Section: Introductionmentioning

confidence: 99%

Effects of Streamlining a Bluff Body in the Laminar Vortex Shedding Regime

Dobriyal

Mishra

Bölander

et al. 2019

Journal of Fluids Engineering

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Two-dimensional flow over bluff bodies is studied in the unsteady laminar flow regime using numerical simulations. In previous investigations, lift and drag forces have been studied over different cross-sectional shapes like circles, squares, and ellipses. We aim to extend the previous research by studying the variation of hydrodynamic forces as the shape of the body changes from a circular cylinder to a more streamlined or a bluffer body. The different body shapes are created by modifying the downstream circular arc of a circular cylinder into an ellipse, hence elongating or compressing the rear part of the body. The precise geometry of the body is quantified by defining a shape factor. Two distinct ranges of shape factors with fundamentally different behavior of lift and drag are identified. The geometry constituting the limit is where the rear part ellipse has a semi-minor axis of half the radius of the original circle, independent of the Reynolds number. On the other hand, the vortex shedding frequency decreases linearly over the whole range of shape factors. Furthermore, the variation of the forces and frequency with Reynolds number, and how the relations vary with the shape factor are reported.

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Section: Introductionmentioning

confidence: 99%

Effects of Streamlining a Bluff Body in the Laminar Vortex Shedding Regime

Dobriyal

Mishra

Bölander

et al. 2019

Journal of Fluids Engineering

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“…In general, however, this range of Re is too low to be directly applicable in UAV design. Kim and Sengupta (2005) focused their computational study on the unsteady viscous flow over two dimensional elliptic cylinders by solving the incompressible Navier-Stokes equations for thickness-to-chord ratios of 0.6, 0.8, 1.0 and 1.2, and Re ranging from 200-1000. The total drag force on elliptic cylinders during unsteady viscous airflow mostly comes from the pressure drag force, which increases with an increase of either thickness-to-chord ratio or Re.…”

Section: Literature Reviewmentioning

confidence: 99%

Prediction of Aerodynamic Characteristics for Elliptic Airfoils in Unmanned Aerial Vehicle Applications

Chitta¹,

Dhakal²,

Walters³

2012

Low Reynolds Number Aerodynamics and Transition

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Mechanism of unconventional aerodynamic characteristics of an elliptic airfoil

Sun

Gao

et al. 2015

Chinese Journal of Aeronautics

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The aerodynamic characteristics of elliptic airfoil are quite different from the case of conventional airfoil for Reynolds number varying from about 10 4 to 10 6 . In order to reveal the fundamental mechanism, the unsteady flow around a stationary two-dimensional elliptic airfoil with 16% relative thickness has been simulated using unsteady Reynolds-averaged Navier-Stokes equations and the c À Re ht transition turbulence model at different angles of attack for flow Reynolds number of 5 · 10 5 . The aerodynamic coefficients and the pressure distribution obtained by computation are in good agreement with experimental data, which indicates that the numerical method works well. Through this study, the mechanism of the unconventional aerodynamic characteristics of airfoil is analyzed and discussed based on the computational predictions coupled with the wind tunnel results. It is considered that the boundary layer transition at the leading edge and the unsteady flow separation vortices at the trailing edge are the causes of the case. Furthermore, a valuable insight into the physics of how the flow behavior affects the elliptic airfoil's aerodynamics is provided.

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Unsteady Viscous Flow over Elliptic Cylinders at Various Thickness with Different Reynolds Numbers

Cited by 5 publications

References 18 publications

Effects of Streamlining a Bluff Body in the Laminar Vortex Shedding Regime

Effects of Streamlining a Bluff Body in the Laminar Vortex Shedding Regime

Prediction of Aerodynamic Characteristics for Elliptic Airfoils in Unmanned Aerial Vehicle Applications

Mechanism of unconventional aerodynamic characteristics of an elliptic airfoil

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