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How strain and spin may make a star bi-polar

Citation

Forbes, LK, How strain and spin may make a star bi-polar, Journal of Fluid Mechanics, 746 pp. 332-367. ISSN 0022-1120 (2014) [Refereed Article]


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Copyright Statement

Copyright 2014 Cambridge University Press

DOI: doi:10.1017/jfm.2014.130

Abstract

A previous study by Forbes (ANZIAM J., vol. 53, 2011, pp. 87121) has argued that, when a light fluid is injected from a point source into a heavier ambient fluid, the interface between them is most unstable to perturbations at the lowest spherical mode. This means that, regardless of initial conditions, the outflow from a point source eventually becomes a one-sided jet. However, two-sided (bi-polar) outflows are nevertheless often observed in astrophysics, in apparent contradiction to this prediction. While there are many possible explanations for this fact, the present paper considers the effect of a straining flow in the ambient fluid. In addition, solid-body rotation in the inner fluid is also accounted for, in a Boussinesq viscous model. It is shown analytically that there are circumstances under which straining flow alone is sufficient to convert the one-sided jet into a genuine bi-polar outflow, in linearized theory. This is confirmed in a numerical solution of a viscous model of the flow, based on a spectral solution technique that accounts for nonlinear effects. Rotation can also generate flows that are two-sided, and this is likewise revealed through an asymptotic analysis and numerical solutions of the nonlinear equations.

Item Details

Item Type:Refereed Article
Keywords:fingering instability, one-sided outflow, general fluid mechanics, mathematical foundations
Research Division:Mathematical Sciences
Research Group:Applied Mathematics
Research Field:Theoretical and Applied Mechanics
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Mathematical Sciences
Author:Forbes, LK (Professor Larry Forbes)
ID Code:97605
Year Published:2014
Funding Support:Australian Research Council (DP140100094)
Deposited By:Mathematics and Physics
Deposited On:2015-01-02
Last Modified:2016-06-27
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