研究成果・発表論文

Magnetohydrodynamic simulation code CANS+: Assessments and applications

Matsumoto, Yosuke,   Asahina, Yuta,   Kudoh, Yuki,   Kawashima, Tomohisa,   Matsumoto, Jin,   Takahashi, Hiroyuki R.,   Minoshima, Takashi,   Zenitani, Seiji,   Miyoshi, Takahiro,   & Matsumoto, Ryoji


要旨
We present a new magnetohydrodynamic (MHD) simulation package with the aim of providing accurate numerical solutions to astrophysical phenomena where discontinuities, shock waves, and turbulence are inherently important. The code implements the Harten-Lax-van Leer-discontinuitues (HLLD) approximate Riemann solver, the fifth-order-monotonicity-preserving interpolation (MP5) scheme, and the hyperbolic divergence cleaning method for a magnetic field. This choice of schemes has significantly improved numerical accuracy and stability, and saved computational costs in multidimensional problems. Numerical tests of one- and two- dimensional problems show the advantages of using the high-order scheme by comparing with results from a standard second-order total variation diminishing monotonic upwind scheme for conservation laws (MUSCL) scheme. The present code enables us to explore the long-term evolution of a three-dimensional accretion disk around a black hole, in which compressible MHD turbulence causes continuous mass accretion via nonlinear growth of the magneto-rotational instability (MRI). Numerical tests with various computational cell sizes exhibits a convergent picture of the early nonlinear growth of the MRI in a global model, and indicates that the MP5 scheme has more than twice the resolution of the MUSCL scheme in practical applications.






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