Hypersonic jets in astrophysical conditions: focus on spreading and asymmetric stability properties

Belan, M.; Tordella, Daniela; Ponte, S. De; Mignone, A.; Massaglia, S.

doi:10.1088/1367-2630/16/8/085002

Cited by 6 publications

(1 citation statement)

References 27 publications

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“…As the jet enters into the ambient medium, it immediately forms a bow-shock that pushes the ambient material to its sides. The overall morphology of the jet is determined primarily by the Mach number, the density contrast (a result that has also been confirmed in laboratory experiments (Belan et al 2013(Belan et al , 2014) and the magnetic field strength. The processed material gets heated and forms the cocoon as shown in Fig.…”

Section: Axisymmetric Mhd Jetssupporting

confidence: 54%

Astrophysical fluid simulations of thermally ideal gases with non-constant adiabatic index: numerical implementation

Vaidya

Mignone

Bodo

et al. 2015

A&A

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Context. An equation of state (EoS) is a relation between thermodynamic state variables and it is essential for closing the set of equations describing a fluid system. Although an ideal EoS with a constant adiabatic index Γ is the preferred choice owing to its simplistic implementation, many astrophysical fluid simulations may benefit from a more sophisticated treatment that can account for diverse chemical processes. Aims. In the present work we first review the basic thermodynamic principles of a gas mixture in terms of its thermal and caloric EoS by including effects like ionization, dissociation, and temperature dependent degrees of freedom such as molecular vibrations and rotations. The formulation is revisited in the context of plasmas that are either in equilibrium conditions (local thermodynamicor collisional excitation-equilibria) or described by non-equilibrium chemistry coupled to optically thin radiative cooling. We then present a numerical implementation of thermally ideal gases obeying a more general caloric EoS with non-constant adiabatic index in Godunov-type numerical schemes. Methods. We discuss the necessary modifications to the Riemann solver and to the conversion between total energy and pressure (or vice versa) routinely invoked in Godunov-type schemes. We then present two different approaches for computing the EoS. The first employs root-finder methods and it is best suited for EoS in analytical form. The second is based on lookup tables and interpolation and results in a more computationally efficient approach, although care must be taken to ensure thermodynamic consistency. Results. A number of selected benchmarks demonstrate that the employment of a non-ideal EoS can lead to important differences in the solution when the temperature range is 500−10 4 K where dissociation and ionization occur. The implementation of selected EoS introduces additional computational costs although the employment of lookup table methods (when possible) can significantly reduce the overhead by a factor of ∼3−4.

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Section: Axisymmetric Mhd Jetssupporting

confidence: 54%