University of Cambridge > Talks.cam > DAMTP Astro Mondays > An optimal transient growth of small perturbations in thin gaseous discs

An optimal transient growth of small perturbations in thin gaseous discs

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If the matter rotates around a point-mass gravitating body it can form an axisymmetric torus that has a rotational profile determined by its pressure gradient distribution. Although a thick torus with a non-keplerian rotation bounded by the free surface has a set of global exponentially growing modes when it approaches a thin disc with an almost keplerian rotation this global acoustic instability ceases promptly and we get a nearly stable shearing flow. However, a substantial transient growth of linear perturbations measured by the evolution of their acoustic energy is possible even in this case. This fact is demonstrated for a simple model of a non-viscous polytropic thin disc of a finite radial size where small global adiabatic perturbations are considered as linear combinations of neutral modes with a corotational radius located beyond the outer boundary of the flow.

This talk is part of the DAMTP Astro Mondays series.

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