Thursday 15 Nov 2018[Joint GAFD/Astrophysics Seminar] Celestial fluid mechanics: new perspectives on the hydrodynamics of astrophysical discs

Prof. Gordon Ogilvie - University of Cambridge

Harrison H103 14:30-16:30

Astrophysical discs often deviate from the circular, planar forms
assumed in classical accretion-disc theory. Gravitational interaction
with orbital companions can cause discs to become elliptical, warped
and tidally deformed. In this talk I will discuss some physical
consequences of these situations and introduce some novel theoretical
methods for studying them. Generalizations of the shearing-box model,
incorporating the oscillatory geometry experienced by orbiting fluid
elements, reveal hydrodynamic turbulence that results from the
destabilization of internal waves. Many aspects of warped discs can
be alternatively be studied using a standard shearing box that
undergoes modulated vertical oscillations. The nonlinear secular
hydrodynamics of eccentric discs can be discussed in a Hamiltonian
framework that connects with methods of celestial mechanics. Finally,
a new affine model of astrophysical discs augments the computationally
convenient equations of 2D hydrodynamics with the additional degrees
of freedom needed to describe several of these situations.

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