翻訳と辞書 Words near each other ・ Stole Aranđelović ・ Stole Dimitrievski ・ Stole Janković ・ Stole Popov ・ Stole the Show ・ Stolec ・ Stolec Poduchowny ・ Stolec, Lower Silesian Voivodeship ・ Stokes Inlet ・ Stokes Landing, California ・ Stokes law ・ Stokes line ・ Stokes mortar ・ Stokes Mountain ・ Stokes National Park ・ Stokes number ・ Stokes operator ・ Stokes operators ・ Stokes parameters ・ Stokes Peaks ・ Stokes phenomenon ・ Stokes radius ・ Stokes Range ・ Stokes relations ・ Stokes River ・ Stokes shift ・ Stokes State Forest ・ Stokes stream function ・ Stokes Township ・ Stokes Township, Itasca County, Minnesota Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Stokes number ： ウィキペディア英語版 Stokes number The Stokes number (Stk), named after George Gabriel Stokes, is a dimensionless number characterising the behavior of particles suspended in a fluid flow. The Stokes number is defined as the ratio of the characteristic time of a particle (or droplet) to a characteristic time of the flow or of an obstacle, or :$\backslash mathrm\; =\; \backslash frac$ where $t\_0$ is the relaxation time of the particle (the time constant in the exponential decay of the particle velocity due to drag), $u\_0$ is the fluid velocity of the flow well away from the obstacle and $l\_0$ is the characteristic dimension of the obstacle (typically its diameter). A particle with a low Stokes number follows fluid streamlines (perfect advection), while a particle with a large Stokes number is dominated by its inertia and continues along its initial trajectory. In the case of Stokes flow, which is when the particle (or droplet) Reynolds number is low enough that the particle drag coefficient is inversely proportional to the Reynolds number itself, the characteristic time of the particle can be defined as : $t\_0\; =\; \backslash frac$ where $\backslash rho\_d$ is the particle density, $d\_d$ is the particle diameter and $\backslash mu\_g$ is the gas dynamic viscosity. In experimental fluid dynamics, the Stokes number is a measure of flow tracer fidelity in particle image velocimetry (PIV) experiments where very small particles are entrained in turbulent flows and optically observed to determine the speed and direction of fluid movement (also known as the velocity field of the fluid). For acceptable tracing accuracy, the particle response time should be faster than the smallest time scale of the flow. Smaller Stokes numbers represent better tracing accuracy; for $\backslash mathrm\; \backslash gg\; 1$, particles will detach from a flow especially where the flow decelerates abruptly. For $\backslash mathrm\; \backslash ll1$, particles follow fluid streamlines closely. If $\backslash mathrm\; \backslash ll\; 0.1$, tracing accuracy errors are below 1%. == Application to anisokinetic sampling of particles == For example, the selective capture of particles by an aligned, thin-walled circular nozzle is given by Belyaev and Levin as: :$c\; /\; c\_0\; =\; 1\; +\; (u\_\; /\; u\; -1)\; \backslash left(1-\backslash frac)\}\backslash right)$ where $c$ is particle concentration, $u$ is speed, and the subscript 0 indicates conditions far upstream of the nozzle. The characteristic distance is the diameter of the nozzle. Here the Stokes number is calculated, :$\backslash mathrm\; =\; \backslash frac\}$ where $V\_$ is the particle's settling velocity, $d$ is the sampling tubes inner diameter, and $g$ is the acceleration of gravity. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Stokes number」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.