MAGMA：一个用于合并应用的三维拉格朗日磁流体动力学程序
MAGMA: a 3D, Lagrangian magnetohydrodynamics code for merger applications
摘要：
我们提出了一个新的，完全拉格朗日磁流体动力学代码，是基于SPH方法。自引力流体动力学方程是从拉格朗日量自洽导出的，并考虑了流体动力学方程和重力加速度方程中的可变平滑长度（“grad-h”-）项。磁场的演化是用所谓的欧拉势来表示的，欧拉势与流体平流，从而保证了MHD通量冻结条件。该公式等价于矢量势方法，因此通过构造满足$\vec{\nabla}\cdot\vec{B}=0$ -约束。广泛的测试在一个，两个和三个维度。测试表明，优秀的守恒性质的代码，并显示了明显的优越性，早期的磁SPH配方的欧拉潜力。
英文摘要：
We present a new, completely Lagrangian magnetohydrodynamics code that is based on the SPH method. The equations of self-gravitating hydrodynamics are derived self-consistently from a Lagrangian and account for variable smoothing length (``grad-h''-) terms in both the hydrodynamic and the gravitational acceleration equations. The evolution of the magnetic field is formulated in terms of so-called Euler potentials which are advected with the fluid and thus guarantee the MHD flux-freezing condition. This formulation is equivalent to a vector potential approach and therefore fulfills the $\vec{\nabla}\cdot\vec{B}=0$-constraint by construction. Extensive tests in one, two and three dimensions are presented. The tests demonstrate the excellent conservation properties of the code and show the clear superiority of the Euler potentials over earlier magnetic SPH formulations.
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