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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 compared the experimentally determined dependence of the total drag coefficient on the Reynolds number and the CFD simulations in this work and observed that spacers with equal filament diameters usually result in higher pressure drop across the channel and such symmetric spacers also result in a more uniform shear rate at the top and bottom faces of the test cell.

187 citations

Journal ArticleDOI
TL;DR: An immersed boundary lattice Boltzmann approach to simulate deformable capsules in flows is developed and validated for the Laplace relationship, the dispersion relationship for interfacial waves and the drag coefficient for cylinders.
Abstract: In this paper, we develop an immersed boundary lattice Boltzmann approach to simulate deformable capsules in flows. The lattice Boltzmann method is utilized to solve the incompressible flow field over a regular Eulerian grid, while the immersed boundary method is employed to incorporate the fluid–membrane interaction with a Lagrangian representation of the capsule membrane. This algorithm was validated for the Laplace relationship, the dispersion relationship for interfacial waves and the drag coefficient for cylinders; excellent agreement with theoretical results was observed. Furthermore, simulations of single and multiple red blood cells in shear and channel flows were performed. Several characteristic hemodynamic and hemorheological features were successfully reproduced, including the tank-treading motions, cell migration from the vessel wall, slipper-shaped cell deformation, cell-free layers, blunt velocity profiles and the Fahraeus effect. These simulations therefore demonstrate the potential usefulness of this computational model for microscopic biofluidic systems. However, extension of this algorithm to three-dimensional situations is necessary for more realistic simulations.

187 citations

Journal ArticleDOI
TL;DR: In this paper, a simple drag partition theory is developed for the classical problem of boundary layer flows over regular arrays of two- or three-dimensional roughness elements, which is used for determining the contribution of form drag on pressure ridges to the total wind stress on the arctic pack ice.
Abstract: A simple drag partition theory is developed for the classical problem of boundary layer flows over regular arrays of two- or three-dimensional roughness elements. The theoretical expression for the ratio of the form drag on these elements to the total drag is shown to be in good agreement with wind tunnel observations. It is used for determining the contribution of form drag on pressure ridges to the total wind stress on the arctic pack ice. The theory also leads to an expression for the large-scale roughness parameter as a function of mean ridge height, ridging intensity, small-scale or local roughness parameter, and an average form drag coefficient. It is required for determining the average wind stress over large areas of the Arctic on a routine basis, using the so-called geostrophic drag method, as envisaged in the Aidjex program.

187 citations

Journal ArticleDOI
TL;DR: In this paper, the authors apply the immersed-boundary method to simulate 2-and 3-dimensional viscous incompressible flows interacting with moving solid boundaries using direct-momentum forcing on a Cartesian grid by combining "solid-body forcing" at solid nodes and interpolation on neighboring fluid nodes.

186 citations

Journal ArticleDOI
TL;DR: In this article, the authors present closures for the drag and virtual mass force terms appearing in a two-fluid model for flow of a mixture consisting of uniformly sized gas bubbles dispersed in a liquid.
Abstract: We present closures for the drag and virtual mass force terms appearing in a two-fluid model for flow of a mixture consisting of uniformly sized gas bubbles dispersed in a liquid. These closures were deduced through computational experiments performed using an implicit formulation of the lattice Boltzmann method with a BGK collision model. Unlike the explicit schemes described in the literature, this implicit implementation requires iterative calculations, which, however, are local in nature. While the computational cost per time step is modestly increased, the implicit scheme dramatically expands the parameter space in multiphase flow calculations which can be simulated economically. The closure relations obtained in our study are limited to a regular array of uniformly sized bubbles and were obtained by simulating the rise behaviour of a single bubble in a periodic box. The effect of volume fraction on the rise characteristics was probed by changing the size of the box relative to that of the bubble. While spherical bubbles exhibited the expected hindered rise behaviour, highly distorted bubbles tended to rise cooperatively. The closure for the drag force, obtained in our study through computational experiments, captured both hindered and cooperative rise. A simple model for the virtual mass coefficient, applicable to both spherical and distorted bubbles, was also obtained by fitting simulation results. The virtual mass coefficient for isolated bubbles could be correlated with the aspect ratio of the bubbles.

184 citations


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