Non-linear behaviour of warped discs around a central object with a quadrupole moment
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Publication Date
2022-04-19Journal Title
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
ISSN
0035-8711
Publisher
Oxford University Press (OUP)
Type
Article
This Version
AM
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Deng, H., & Ogilvie, G. (2022). Non-linear behaviour of warped discs around a central object with a quadrupole moment. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY https://doi.org/10.1093/mnras/stac858
Abstract
<jats:title>Abstract</jats:title>
<jats:p>The nonlinear behaviour of low-viscosity warped discs is poorly understood. We verified a nonlinear bending-wave theory, in which fluid columns undergo affine transformations, with direct 3D hydrodynamical simulations. We employed a second-order Godunov-type scheme, Meshless Finite Mass (MFM), and also the Smoothed Particle Hydrodynamics (SPH) method, with up to 128M particles. For moderate nonlinearity, MFM maintains well the steady nonlinear warp predicted by the affine model for a tilted inviscid disc around a central object with a quadrupole moment. However, numerical dissipation in SPH is so severe that even a low-amplitude nonlinear warp degrades at a resolution where MFM performs well. A low-amplitude arbitrary warp tends to evolve towards a nonlinear steady state. However, no such state exists in our thin disc with an angular semi-thickness H/R = 0.02 when the outer tilt angle is beyond about 14○. The warp breaks tenuously and reconnects in adiabatic simulations, or breaks into distinct annuli in isothermal simulations. The breaking radius lies close to the location with the most extreme nonlinear deformation. Parametric instability is captured only in our highest-resolution simulation, leading to ring structures that may serve as incubators for planets around binaries.</jats:p>
Sponsorship
STFC (ST/T00049X/1)
Identifiers
External DOI: https://doi.org/10.1093/mnras/stac858
This record's URL: https://www.repository.cam.ac.uk/handle/1810/335456
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