Аннотация
The classical Bondi-Hoyle formula gives the accretion rate onto a point
particle of a gas with a uniform density and velocity. However, the Bondi-Hoyle
problem considers only gas with no net vorticity, while in a real astrophysical
situation accreting gas invariably has at least a small amount of vorticity. We
therefore consider the related case of accretion of gas with constant
vorticity, for the cases of both small and large vorticity. We confirm the
findings of earlier two dimensional simulations that even a small amount of
vorticity can substantially change both the accretion rate and the morphology
of the gas flow lines. We show that in three dimensions the resulting flow
field is non-axisymmetric and time dependent. The reduction in accretion rate
is due to an accumulation of circulation near the accreting particle. Using a
combination of simulations and analytic treatment, we provide an approximate
formula for the accretion rate of gas onto a point particle as a function of
the vorticity of the surrounding gas.
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