# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 5 Search : Stokes
 Navier-Stokes equation   هموگش ِ ناویه-استوکس   hamugeš-e Navier-StokesFr.: équation de Navier-Stokes   One of a set of → differential equations that describes the motion of a → fluid as a function of → pressure, → density, total external force, and → viscosity. See also → Euler equation.Named after Claude-Louis Navier (1785-1836), a French engineer and physicist, and George Gabriel Stokes, → stokes; → equation. stokes (st)   استوکس   stokes (#)Fr.: stokes   The unit of → viscosity in the → cgs system, cm2 s-1, equal to 10-4 m2 s-1.After Sir George Gabriel Stokes (1819-1903), a British mathematician and physicist, who made important contributions to fluid dynamics, optics, and mathematical physics; → Stokes law; → Stokes parameter. Stokes friction factor   کروند ِ مالش ِ استوکس   karvand-e mâleš-e StokesFr.: facteur de friction de Stokes   For the translational motion of a spherical body moving in a → viscous fluid, the proportionality factor between the uniform flow velocity far from the sphere and the drag force, provided no-slip boundary condition and small → Reynolds numbers: f = 6πηR, where η is the Reynolds number and R radius of the sphere.→ Stokes; → friction; → factor. Stokes law   قانون ِ استوکس   qânun-e Stokes (#)Fr.: loi de Stokes   1) Fluid mechanics: At low velocities, the frictional force on a spherical body moving through a fluid at constant velocity is equal to 6πRηv, where R is the radius of the sphere, η the fluid → viscosity, and v the velocity. 2) Spectroscopy: The wavelength of → luminescence excited by radiation is always greater than that of the exciting radiation.→ Stokes; → law. Stokes parameters   پارامون‌های ِ استوکس   pârâmunhâ-ye StokesFr.: paramètres de Stokes   Four parameters which are needed to fully describe the → polarization state of → electromagnetic radiation. They involve the maximum and minimum intensity, the ellipticity, and the direction of polarization. The four Stokes parameters are traditionally defined as follows: I ≡ total intensity. Q ≡ I0 - I90 = difference in intensities between → horizontal and → vertical  → linearly polarized components. U ≡ I+45 - I-45 = difference in intensities between linearly polarized components oriented at +45° and -45° (or 135°). V ≡ Ircp - Ilcp = difference in intensities between right and left → circularly polarized polarized components.→ Stokes; → parameter.