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Ekman pumping in compact astrophysical bodies

Published online by Cambridge University Press:  26 April 2006

Mark Abney  and
Richard I. Epstein
Mark Abney
Affiliation:
Department of Astronomy and Astrophysics, The Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637, USA and NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, IL 60510, USA e-mail: abney@oddjob.uchicago.edu Los Alamos National Laboratory, MS D436, Los Alamos, NM 87545, USA e-mail: epstein@lanl.gov
Richard I. Epstein
Affiliation:
Los Alamos National Laboratory, MS D436, Los Alamos, NM 87545, USA e-mail: epstein@lanl.gov
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Abstract

We examine the dynamics of a rotating viscous fluid following an abrupt change in the angular velocity of the solid bounding surface. We include the effects of a density stratification and compressibility which are important in astrophysical objects such as neutron stars. We confirm and extend the conclusions of previous studies that stratification restricts the Ekman pumping process to a relatively thin layer near the boundary, leaving much of the interior fluid unaffected. We find that finite compressibility further inhibits Ekman pumping by decreasing the extent of the pumped layer and by increasing the time for spin-up. The results of this paper are important for interpreting the spin period discontinuities (‘glitches’) observed in rotating neutron stars.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 312 , 10 April 1996 , pp. 327 - 340
Copyright
© 1996 Cambridge University Press

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