
Figures of equilibrium of an inhomogeneous selfgravitating fluid
Ivan A. Bizyaev^{a}, Alexey V. Borisov^{bca}, Ivan S. Mamaev^{a} ^{a} Udmurt State University, Universitetskaya 1, Izhevsk, 426034, Russia
^{b} Institute of Mathematics and Mechanics of the Ural Branch of RAS,
S. Kovalevskaja str. 16, Ekaterinburg, 620990, Russia
^{c} National Research Nuclear University “MEPhI”, Kashirskoye shosse 31, Moscow, 115409, Russia
Abstract:
This paper is concerned with the figures of equilibrium of a selfgravitating ideal fluid with density stratification and a steadystate velocity field. As in the classical setting, it is assumed that the figure or its layers uniformly rotate about an axis fixed in space. As is well known, when there is no rotation, only a ball can be a figure of equilibrium.
It is shown that the ellipsoid of revolution (spheroid) with confocal stratification, in which each layer rotates with inherent constant angular velocity, is at equilibrium. Expressions are obtained for the gravitational potential, change in the angular velocity and pressure, and the conclusion is drawn that the angular velocity on the outer surface is the same as that of the Maclaurin spheroid. We note that the solution found generalizes a previously known solution for piecewise constant density distribution. For comparison, we also present a solution, due to Chaplygin, for a homothetic density stratification.
We conclude by considering a homogeneous spheroid in the space of constant positive curvature. We show that in this case the spheroid cannot rotate as a rigid body, since the angular velocity distribution of fluid particles depends on the distance to the symmetry axis.
Keywords:
selfgravitating fluid, confocal stratification, homothetic stratification, space of constant curvature.
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UDC:
532.253, 532.5
MSC: 76U05 Received: 12.12.2013 Revised: 24.01.2014
Citation:
Ivan A. Bizyaev, Alexey V. Borisov, Ivan S. Mamaev, “Figures of equilibrium of an inhomogeneous selfgravitating fluid”, Nelin. Dinam., 10:1 (2014), 73–100
Citation in format AMSBIB
\Bibitem{BizBorMam14}
\by Ivan~A.~Bizyaev, Alexey~V.~Borisov, Ivan~S.~Mamaev
\paper Figures of equilibrium of an inhomogeneous selfgravitating fluid
\jour Nelin. Dinam.
\yr 2014
\vol 10
\issue 1
\pages 73100
\mathnet{http://mi.mathnet.ru/nd426}
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http://mi.mathnet.ru/eng/nd426 http://mi.mathnet.ru/eng/nd/v10/i1/p73
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