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: The drag coefficients of a wide range of grains and straws have been measured experimentally by finding the suspension velocities of the particles in an air stream as mentioned in this paper, and the representation of shape is discussed and volume shape factors are proposed for non-spherical particles.
77 citations
TL;DR: In this article, an experimental investigation of flow around a square cylinder placed at various angles with respect to the approach fluid velocity is reported, and the focus of the study is toward examining the sensitivity of the wake properties to the cylinder orientation and Reynolds number.
Abstract: An experimental investigation of flow around a square cylinder placed at various angles with respect to the approach fluid velocity is reported. The focus of the study is toward examining the sensitivity of the wake properties to the cylinder orientation and Reynolds number. Angles of incidence in the range of 0–60° and Reynolds numbers of 1340, 4990, and 9980 have been considered. Velocity measurements have been carried out using an X-wire hotwire anemometer. The Strouhal number and the drag coefficient of the cylinder have been computed from the wake measurements. Utilizing the velocity traces at distinct probe locations in the near and the far wake, statistical properties such as the RMS velocities and the spectra have been obtained. Results obtained in the present work revealed that for a cylinder with zero inclination, flow separates from the corners on the face exposed to the incoming flow. For inclinations greater than zero, the points of separation on the cylinder move downstream and the wake size increases, but the separated shear layer rolls up over a shorter distance. These factors lead to a reduced drag coefficient and a higher Strouhal number. The center-line recovery of the time-averaged velocity and the decay rates of velocity fluctuations depend on the Reynolds number. A marginal effect of the cylinder orientation is also seen.
77 citations
TL;DR: In this paper, a set of field measurements of the drag on model woody debris for conditions that prevail in typical natural streams was performed, where the model debris consisted of PVC "logs" with diameters between 4 and 30 cm.
77 citations
TL;DR: In this article, a method for determining the form drag on irregular sequences of different-sized topographic features is developed for calculating near-boundary flows and sediment transport, which can be used to improve predictions of flow resistance in rivers as well as quantify bank roughness.
Abstract: [1] The size, shape, and spacing of small-scale topographic features found on the boundaries of natural streams, rivers, and floodplains can be quite variable. Consequently, a procedure for determining the form drag on irregular sequences of different-sized topographic features is essential for calculating near-boundary flows and sediment transport. A method for carrying out such calculations is developed in this paper. This method builds on the work of Kean and Smith (2006), which describes the flow field for the simpler case of a regular sequence of identical topographic features. Both approaches model topographic features as two-dimensional elements with Gaussian-shaped cross sections defined in terms of three parameters. Field measurements of bank topography are used to show that (1) the magnitude of these shape parameters can vary greatly between adjacent topographic features and (2) the variability of these shape parameters follows a lognormal distribution. Simulations using an irregular set of topographic roughness elements show that the drag on an individual element is primarily controlled by the size and shape of the feature immediately upstream and that the spatial average of the boundary shear stress over a large set of randomly ordered elements is relatively insensitive to the sequence of the elements. In addition, a method to transform the topography of irregular surfaces into an equivalently rough surface of regularly spaced, identical topographic elements also is given. The methods described in this paper can be used to improve predictions of flow resistance in rivers as well as quantify bank roughness.
77 citations
TL;DR: In this paper, the Reynolds number of cylinders and discs falling in a viscous liquid was determined experimentally for values of the Best number (the product of the drag coefficient and the square of the Reynolds numbers) ranging from 1 to 104.
Abstract: The Reynolds number of cylinders and discs falling in a viscous liquid was determined experimentally for values of the Best number (the product of the drag coefficient and the square of the Reynolds number) ranging from 1 to 104. The results were used to calculate the terminal velocities of plate-like and columnar ice crystals.
77 citations