Piecewise Parabolic Method on a Local Stencil for Magnetized Supersonic Turbulence Simulation - Astrophysics > Astrophysics of GalaxiesReportar como inadecuado




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Abstract: Stable, accurate, divergence-free simulation of magnetized supersonicturbulence is a severe test of numerical MHD schemes and has been surprisinglydifficult to achieve due to the range of flow conditions present. Here wepresent a new, higher order-accurate, low dissipation numerical method whichrequires no additional dissipation or local -fixes- for stable execution. Wedescribe PPML, a local stencil variant of the popular PPM algorithm for solvingthe equations of compressible ideal magnetohydrodynamics. The principaldifference between PPML and PPM is that cell interface states are evolvedrather that reconstructed at every timestep, resulting in a compact stencil.Interface states are evolved using Riemann invariants containing all transversederivative information. The conservation laws are updated in an unsplitfashion, making the scheme fully multidimensional. Divergence-free evolution ofthe magnetic field is maintained using the higher order-accurate constrainedtransport technique of Gardiner and Stone. The accuracy and stability of thescheme is documented against a bank of standard test problems drawn from theliterature. The method is applied to numerical simulation of supersonic MHDturbulence, which is important for many problems in astrophysics, includingstar formation in dark molecular clouds. PPML accurately reproduces inthree-dimensions a transition to turbulence in highly compressible isothermalgas in a molecular cloud model. The low dissipation and wide spectral bandwidthof this method make it an ideal candidate for direct turbulence simulations.



Autor: Sergey D. Ustyugov, Mikhail V. Popov, Alexei G. Kritsuk, Michael L. Norman

Fuente: https://arxiv.org/



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