HERSANT, F.

doi:10.1051/0004-6361/200911865

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HERSANT, F.
Université Sciences et Technologies - Bordeaux 1 [UB]
Laboratoire d'Astrophysique de Bordeaux [Pessac] [LAB]
Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux [L3AB]
Observatoire aquitain des sciences de l'univers [OASU]

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Astronomy and Astrophysics - A&A. 2009, vol. 502, n° 1, p. 385-389

EDP Sciences

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Aims. Collections of dust, grains, and planetesimals are often treated as a pressureless fluid. We study the validity of neglecting the pressure of such a fluid by computing it exactly for the case of particles settling in a disk. Methods. We solve a modified collisionless Boltzmann equation for the particles and compute the corresponding moments of the phase space distribution: density, momentum, and pressure. Results. We find that whenever the Stokes number, defined as the ratio of the gas drag timescale to the orbital timescale, is more than 1/2, the particle fluid cannot be considered as pressureless. While we show it only in the simple case of particles settling in a laminar disk, this property is likely to remain true for most flows, including turbulent flows.< Réduire

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Astrophysics

Instrumentation and Methods for Astrophysics

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On the pressure of collisionless particle fluids. The case of solids settling in disks

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