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Drag coefficient

About: Drag coefficient is a research topic. Over the lifetime, 14471 publications have been published within this topic receiving 303196 citations. The topic is also known as: drag factor.


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Journal ArticleDOI
TL;DR: In this article, the authors used the variable order calculus to determine the region of validity of Tchen's equation for oscillatory flow, where the order of the derivative is fractional but constant, and where the strong non-linearity of the flow requires a variable order derivative.
Abstract: This work advances our understanding of the drag force acting on a particle due to the oscillatory flow of a viscous fluid with finite Reynolds and Strouhal numbers. The drag force is is determined using the novel concept of variable order (VO) calculus, where the order of derivative can vary with the parameters and variables, according to the dynamics of the flow. Using the VO formulation we determine: (i) The region of validity of Tchen's equation for oscillatory flow, (ii) the region where the order of the derivative is fractional but constant, and (iii) the region where the strong non-linearity of the flow requires a variable order derivative to account for the increased complexity of the flow.

107 citations

Proceedings ArticleDOI
01 Jan 1983
TL;DR: In this paper, the passive shock wave/boundary layer interaction control for reducing the drag in 12 percent thick circular arc and 14 percent thick supercritical airfoils was conducted in a 3 in. x 15.4 in. transonic wind tunnel at transonic Mach numbers.
Abstract: An investigation of the passive shock wave/boundary layer interaction control for reducing the drag in 12 percent thick circular arc and 14 percent thick supercritical airfoils was conducted in a 3 in. x 15.4 in. transonic wind tunnel at transonic Mach numbers. A porous surface with a cavity beneath it was positioned on the area of the airfoils, mounted on the test section bottom wall, where the shock wave occurs. The static pressure distributions over the airfoil, the wake impact pressure data for determining the profile drag, and the Schlieren photographs for porous surface airfoils are presented and compared with the results for solid surface airfoils. With the porous surface the normal shock wave for solid surface was changed to a lambda shock wave system, and the wake impact pressure data indicated an appreciable drag reduction for both airfoils with the porous surface at transonic speeds while causing little or no loss of lift. The effect of porosity and cavity size is investigated and off-design performance is discussed.

107 citations

Journal ArticleDOI
TL;DR: In this article, a 2D Unsteady Reynolds-Averaged Navier-Stokes (URANS) model with a standard high Reynolds number k- epsilon turbulence model is evaluated for engineering design in supercritical and upper-transition flow regimes.

106 citations

Journal ArticleDOI
TL;DR: In this article, the effect of fluid elasticity on the drag coefficient in the absence of any significant shear-thinning effects is clearly demonstrated, and a continuous reduction in drag below the Stokes value is observed until an asymptotic reduction of 26% is reached for We >/ 0.7.
Abstract: Drag coefficients are measured for the creeping motion of a sphere in nonshear-thinning elastic fluids. The data obtained cover a Weissenberg number range of 1.66 × 10−4 to 2.02. For 0 ⩽ We ⩽ 0.1 no significant deviation from the Stokes drag is observed as a result of fluid elasticity. For We > 0.1 a continuous reduction in drag below the Stokes value is observed until an asymptotic reduction of 26% is reached for We >/ 0.7. Existing theoretical analyses are inadequate for predicting the reduction in drag observed and its asymptotic value. The effect of fluid elasticity on the drag coefficient in the absence of any significant shear-thinning effects is clearly demonstrated.

106 citations

Book ChapterDOI
01 Jan 1986
TL;DR: The dim ensionless parameter u * 2 /vσ can be used widely as a parameter to describe the overall conditions of air-sea boundary processes, where u* is the friction velocity of air, v is the kinematic viscosity of air and s is the spectral peak frequency of the wind waves as discussed by the authors.
Abstract: The dim ensionless parameter u * 2 /vσ can be used widely as a parameter to describe the overall conditions of air-sea boundary processes, where u* is the friction velocity of air, v is the kinematic viscosity of air and s is the spectral peak frequency of the wind waves A critical value of this parameter for the appreciable commencement of breaking of wind waves is 103 Beyond this value, the percentage of waves passing a fixed point that are breaking, α, and the percentage of whitecap coverage, P, are both approximately proportional to this parameter The number concentration of sea-salt particles containing salt in the vicinity of 10−10 g at the 6-m level is also proportional to this parameter The dimensionless roughness length associated with the air flow over water, u*Z0 /V, also correlates better with this parameter than with a parameter which does not contain the spectral peak frequency This gives an approximate relation of z0 σ/u* = 0025, and a corresponding formula for the drag coefficient is proposed The dimensional and physical interpretation of the parameteru */2/vσ is presented

106 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023307
2022688
2021489
2020504
2019504
2018456