What is it about?
Interiors of planets and stars are usually in the form of spherical layers of fluid. To study the effect of rotation on these layers, we study what happens when a fluid is trapped in between two spheres and they are rotated at different rates. We perform computer simulations and compare with real life experiments and reproduce the experimental results. Oscillatory motions (called "inertial modes") of unknown origin have been observed in this system since experiments in Maryland, USA in 2007. We address this question with a new paradigm involving resonances among different modes. In addition, we also show how these modes change their structure and frequency when the differential rotation is changed.
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Why is it important?
We show how these oscillatory modes, often detected in stars, change from their theoretical selves in the presence of background differential rotation. This has never been done before for realistic flow profiles. This provides a framework of further studying mode modifications by flows which would have profound consequences in terms of mode identification in astrophysical objects. Secondly, we have identified a possible mechanism by which these modes might be generated - providing further insight into the state of the interiors of real astrophysical objects.
Perspectives
This article would help being more attention to this seemingly simple system producing complex fluid dynamics phenomena. Also, in the future, one might include more effects such as addition of magnetic fields or convection to provide a test bed of studying effects of interaction of these effects with shear flow, with profound consequences in study of astrophysical objects.
Ankit Barik
Johns Hopkins University
Read the Original
This page is a summary of: Triadic resonances in the wide-gap spherical Couette system, Journal of Fluid Mechanics, March 2018, Cambridge University Press,
DOI: 10.1017/jfm.2018.138.
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