Mathematical modeling of a jet in the vicinity of a compact object

Jet acceleration in a variety of mass source model options

“…As in [18], we construct the boundary conditions by placing the sound point of the flow onto the outflow boundary in the case that the true sound point lies outside the calculation region. The calculations show [13] that the use of the ordinary sound point ( where is the gas sound speed) for a nonre flecting approximation of boundary conditions in the magnetic hydrodynamics proves to be sufficient, and there is no need to consider specifically Alfven's, rapid and slow magnetic sound velocities.…”

“…One of the variants is a "tight switch": with magnetic force lines to achieve an angle with the normal (we denote it by ) of 30°, the type of the boundary condition changes from impermeability to the free inflow of mass into the reference region with the mentioned way of the selection of the speed and with the condition that the normal derivative density on the disc surface equals zero. It is this variant that was executed in [12,13] and is discussed below. We note that the impermeability condition provides equality to zero for the speed component normal to the disc at the free change of its other components.…”

“…In [12,13] and in this work it is assumed that the speed of the outflow of mass from the disc is deter mined by the speed of flow over the disc surface. In the execution of boundary conditions in the fictitious cell, we assign it to be equal to speed module in the boundary cell and co directed with the relevant mag netic force line.…”

“…Notation and system of differential equations. Following [12,13], for a description of the processes with the mass surrounding the accretion disc, we use a system of nonstationary equations of ideal magnetic hydrodynamics of compressible plasma in a 2D axisymmetric formulation using cylindrical coordinates…”

“…In this work we consider a model of the jet outflow formation inside a thick accretion disc surrounding the gravitating compact object considered within the framework of assumptions made in [7,12,13]. A spe cial focus is made on the mass source options for the formed outflow and on the physical mathematical description of the source within this model.…”