Topic
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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TL;DR: In this article, a discrete particle method based on molecular dynamics techniques was used to explore the mechanisms underlying the formation of heterogeneous flow structures in gas-particle flows, and the impact of non-linear drag force on the flow structure formation in dense gas-fluidized beds was examined for both ideal and non-ideal particles.
131 citations
TL;DR: Examination of the marginal effects of small changes of speed, on power and lift:drag ratio, indicates that flying at the maximum range speed on migration may not represent an 'optimal' or even a practical strategy and that cruising speeds may be limited by the muscle power available or by aerobic capacity.
Abstract: Previously published field observations of the air speeds of 36 species of birds, all observed by the same method (ornithodolite), were compared with estimates of the corresponding minimum power speeds, calculated with a default body drag coefficient of 0.1. This value, which was derived from recent wind tunnel studies, represents a downward revision from default values previously used and leads, in turn, to an upward revision of estimated minimum power speeds. The mean observed air speeds are now distributed around the minimum power speed, rather than in between the speeds for minimum power and maximum range, as they were before. Although the field data do not represent migration, examination of the marginal effects of small changes of speed, on power and lift:drag ratio, indicates that flying at the maximum range speed on migration may not represent an 'optimal' or even a practical strategy and that cruising speeds may be limited by the muscle power available or by aerobic capacity. Caution in constructing 'optimisation' theories is indicated.
131 citations
TL;DR: In this paper, the XFOIL code, the Shear Stress Transport k − ω turbulence model and a refurbished version of k − k l− ω transition model were used to predict the airfoil aerodynamic performance at low Reynolds numbers (around 2.0 × 10 5 ).
131 citations
TL;DR: In this article, an analytic solution at the 10th order of approximation for the steady-state laminar viscous past a sphere in a uniform stream governed by the exact, fully non-linear Navier}Stokes equations is given.
Abstract: We give an analytic solution at the 10th order of approximation for the steady-state laminar viscous #ows past a sphere in a uniform stream governed by the exact, fully non-linear Navier}Stokes equations. A new kind of analytic technique, namely the homotopy analysis method, is applied, by means of which Whitehead's paradox can be easily avoided and reasonably explained. Di!erent from all previous perturbation approximations, our analytic approximations are valid in the whole "eld of #ow, because we use the same approximations to express the #ows near and far from the sphere. Our drag coe$cient formula at the 10th order of approximation agrees better with experimental data in a region of Reynolds number R (30, which is considerably larger than that (R (5) of all previous theoretical ones. 2001 Elsevier Science Ltd. All rights reserved.
130 citations
TL;DR: In this paper, the authors describe a numerical study on the steady flow of an incompressible Newtonian fluid past a circular cylinder confined in a plane rectangular channel and present flow parameters such as drag coefficient, length of the recirculation zone, and the angle of separation as functions of the Reynolds number and blockage ratio.
Abstract: This paper describes a numerical study on the steady flow of an incompressible Newtonian fluid past a circular cylinder confined in a plane rectangular channel. Using FLUENT (version 6), two-dimensional steady state computations were carried out for an uniform inlet velocity and for different values of the Reynolds numbers in the range between 0.1 and 200 and blockage ratios (ratio of the channel width to the cylinder diameter) in the range between 1.54 and 20. The flow parameters such as drag coefficient, length of the recirculation zone, and the angle of separation are presented as functions of the Reynolds number and blockage ratio. The total drag coefficient (CD) was found to decrease with an increase in the blockage ratio (λ) for a fixed value of the Reynolds number (Re) and to decrease with increasing Reynolds number for a fixed value of λ. Similarly, for a fixed value of λ, both the angle of separation and the length of the recirculation zone increase with the increasing Reynolds number.
130 citations