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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 paper, Papanastasiou et al. used the Bingham constitutive equation with an appropriate modification, which applies everywhere in the flow field in both yielded and practically unyielded regions.
Abstract: Numerical simulations have been undertaken for the creeping flow of a Bingham plastic past a sphere contained in a cylindrical tube. Different diameter ratios have been studied ranging from 2:1 to 50:1. The Bingham constitutive equation is used with an appropriate modification proposed by Papanastasiou, which applies everywhere in the flow field in both yielded and practically unyielded regions. The emphasis is on determining the extent and shape of unyielded/yielded regions along with the drag coefficient for the whole range of Bingham numbers. The present results extend previous simulations for creeping flow of a sphere in an infinite medium and provide calculations of the Stokes drag coefficient in the case of wall effects.

176 citations

Journal ArticleDOI
TL;DR: In this article, the effect of a few relatively large bubbles injected near the walls on the wall drag in the minimum turbulent channel was examined by direct numerical simulations, and the results showed that deformable bubbles can lead to significant reduction of the wall drifts by suppression of streamwise vorticity.
Abstract: The effect of a few relatively large bubbles injected near the walls on the wall drag in the “minimum turbulent channel” is examined by direct numerical simulations. A front-tracking/finite-volume method is used to fully resolve all flow scales including the bubbles and the flow around them. The Reynolds number, using the friction velocity and the channel half-height, is 135 and the bubbles are 54 wall units in diameter. The results show that deformable bubbles can lead to significant reduction of the wall drag by suppression of streamwise vorticity. Less deformable bubbles, on the other hand, are slowed down by the viscous sublayer and lead to a large increase in drag.

176 citations

Journal ArticleDOI
TL;DR: In this article, the authors developed a drag correlation applicable to the full range of void fractions and Reynolds numbers by blending the Hill-Koch-Ladd (HKL) drag correlation with known limiting forms of the gas-solids drag function such that the blended function is continuous with respect to Reynolds number and void fraction.

176 citations

Journal ArticleDOI
TL;DR: In this article, gas dispersion in a double turbine baffled tank is modeled using a commercial computational fluid dynamics (CFD) code FLUENT 6.1 (Fluent Inc., USA) in order to account for the combined effect of bubble break-up and coalescence in the tank.

175 citations

Journal ArticleDOI
TL;DR: Zeng et al. as mentioned in this paper characterized the structure of the wake for a stationary particle in a linear shear flow and compared with those for a particle moving parallel to a wall in a quiescent ambient flow.
Abstract: To understand and better model the hydrodynamic force acting on a finite-sized particle moving in a wall-bounded linear shear flow, here we consider the two limiting cases of (a) a rigid stationary spherical particle in a linear wall-bounded shear flow and (b) a rigid spherical particle in rectilinear motion parallel to a wall in a quiescent ambient flow. In the present computations, the particle Reynolds number ranges from 2 to 250 at separation distances to the wall from nearly sitting on the wall to far away from the wall. First we characterize the structure of the wake for a stationary particle in a linear shear flow and compare with those for a particle moving parallel to a wall in a quiescent ambient [see L. Zeng, S. Balachandar, and P. Fischer, J. Fluid Mech. 536, 1 (2005)]. For both these cases we present drag and lift results and obtain composite drag and lift correlations that are valid for a wide range of Re and distance from the wall. These correlations have been developed to be consistent with all available low Reynolds number theories and approach the appropriate uniform flow results at large distance from the wall. Particular attention is paid to the case of particle in contact with the wall and the computational results are compared with those from experiments.

175 citations


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