Structure of Blastwaves in a Magnetized Medium

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Session 41 -- Computational Astrophysics II
Display presentation, Wednesday, 1, 1994, 9:20-6:30

[41.16] Structure of Blastwaves in a Magnetized Medium

Dongsu Ryu (Chungnam National University, Korea), T. W.~Jones (U.~of Minnesota), Adam Frank (U.~of Minnesota)

We present multidimensional simulations of adiabatic blastwaves propagating through a magnetized ideal medium. Simulations have been done with a multidimensional magnetohydrodynamic (MHD) code, which was built by extending a one-dimensional code described in Ryu and Jones (1994) using a Strang-type operator splitting method. The constraint of a divergence-free field was enforced exactly by adding a necessary correction calculated in a separate step. Extensive tests including two-dimensional MHD shock tubes proved the ability to capture discontinuities in all three MHD waves families as well as contact and tangential discontinuities

In this poster, we address specifically the question on the existence of intermediate shocks suggested to form in concave fronts around the magnetic pole (e.~g. , Ferri\'ere, Mac Low, and Zweibel, 1992). In our simulations with two-dimensional magnetic field, where the third component of field has been suppressed, we have confirmed the reversal of the transverse magnetic field in the concave fronts but the structures formed resemble fast compound structures, which are composed of intermediate shocks (so called the ``1-3'' intermediate shocks) preceded by fast rarefaction waves. However, we suggest that those intermediate shocks or compound structures are artifacts of the two-dimensional nature of the calculations. In simulations where all the three components of magnetic field are allowed, the transverse magnetic field should be reversed only in rotational discontinuities or tangential discontinuities.

Support for this work at the University of Minnesota is provided through the NSF, NASA and the University of Minnesota Supercomputer Institute. DR also acknowledges the support by the Non-Directed Research Fund of the Korea Research Foundation 1993.

{\noindent Reference:\hfil\break Ryu, D.~and Jones, T.~W., 1994, in preparation.\hfil\break Ferri\'ere, K.~M., Mac Low, M.-M., and Zweibel, E.~G., 1992, Ap.~J., 375, 239}

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