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 paper, the wake of a cylinder performing rotary oscillations around its axis at moderate Reynolds number was studied and it was observed that the structure of the vortex shedding is strongly affected by the forcing parameters.
Abstract: We study the wake of a cylinder performing rotary oscillations around its axis at moderate Reynolds number. We observe that the structure of the vortex shedding is strongly affected by the forcing parameters. The forced wake is characterized by a ‘lock-in’ region where the vortices are shed at the forcing frequency and a region where the vortices can be reorganized to give a second frequency close to those observed for the unforced wake. We show that these modifications of the wake structure change the dynamic of the fluctuations downstream from the cylinder. We vary the amplitude and the frequency of the oscillations and study the consequences of these modifications on the mean flow and the global drag applied on the cylinder. We then discuss the mechanism responsible for the modification of the fluctuations and the modification of the drag coefficient.
120 citations
TL;DR: In this article, the authors adopt an approach employed in terrestrial ocean modeling, where a significant portion of tidal dissipation arises due to bottom drag, with the drag coefficient O (0.001) being relatively well-established.
119 citations
TL;DR: In this paper, a semi-empirical steady-state model of a finned axisymmetric body is developed and used to compute hull -fin mutual interference factors and cross flow drag coefficients from wind tunnel data on five aerostats and airships.
Abstract: A semi-empirical steady-state model of a finned axisymmetric body is developed and used to compute hull -fin mutual interference factors and cross flow drag coefficients from wind tunnel data on five aerostats and airships. The results are in general agreement with expectations from theory and provide a b asis for predicting aerodynamic coefficients. The model is extended to unsteady motion by considering the local flow on finite hull segments and the fins. This dynamic model is applicable to non-linear simulations and the computation of rotational stability derivatives for which equations are derived. For one zerostat, rotational stability derivatives calculated from static wind tunnel data are compared with experimental results from a whirl ing-arm tow tank.
119 citations
TL;DR: In this paper, the impact of dry granular flows consisting of rock fragments and other particles resulting from shallow slope failures on retaining structures has been systematically researched and is not covered by current design codes.
Abstract: Shallow slope failure in mountainous regions is a common and emergent hazard in terms of its damage to important traffic routes and local communities. The impact of dry granular flows consisting of rock fragments and other particles resulting from shallow slope failures on retaining structures has yet to be systematically researched and is not covered by current design codes. As a preliminary study of the impact caused by dry granular flows, a series of dry granular impact experiments were carried out for one model of a retaining wall. It was indirectly verified that the total normal force exerted on a retaining wall consists of a drag force (Fd), a gravitational and frictional force (Fgf), and a passive earth force (Fp), and that the calculation of Fd can be based on the empirical formula defined in NF EN Eurocode 1990 (Eurocode structuraux. Base de calcul des structures, AFNOR La plaine Saint Denis, 2003). It was also indirectly verified that, for flow with Froude number from 6 to 11, the drag coefficient (Cd) can be estimated using the previously proposed empirical parameters.
119 citations
TL;DR: In this article, three hypotheses were proposed to understand the basic characteristics of the observed S-shaped wind profile and the exponential flux profile within forest canopies, and the relationship between these fundamental profiles was well established by combining the postulated hypotheses with momentum equations.
Abstract: To understand the basic characteristics of the observed S-shaped wind profile and the exponential flux profile within forest canopies, three hypotheses are postulated. The relationship between these fundamental profiles is well established by combining the postulated hypotheses with momentum equations. Robust agreements between theoretical predictions and observations indicate that the nature of momentum transfer within canopies can be well understood by combining the postulated hypotheses and momentum equations. The exponential Reynolds stress profiles were successfully predicted by the leaf area index (LAI) profile alone. The characteristics of the S-shaped wind profile were theoretically explained by the plant morphology and local drag coefficient distribution. Predictions of maximum drag coefficient were located around the maximum leaf area level for most forest canopies but lower than the maximum leaf area level for a corn canopy. A universal relationship of the Reynolds stress between the t...
119 citations