In the solar coronal numerical simulation, the coronal heating/acceleration and the magnetic divergence cleaning techniques are very important. The Coronal Interplanetary-Total Variation Diminishing (COIN-TVD) magnetohydrodynamic (MHD) model is developed in recent years that can effectively realize the coronal-interplanetary three-dimensional (3D) solar wind simulation. In this paper, we focus on the 3D coronal solar wind simulation by using the COIN-TVD MHD model. In order to simulate the heating and acceleration of solar wind in coronal region, the volume heating term in the model is improved efficiently. Then, the influence of the different methods to reduce the ∇⋅B constrain error on the coronal solar wind structure is discussed. Here, we choose Carrington Rotation (CR) 2199 as a study case, and try to make a comparison of the simulation results among the different magnetic divergence cleaning methods, including the diffusive method, the Powell method and the composite diffusive/Powell method, by using 3D COIN-TVD MHD model. Our simulation results show that with the different magnetic divergence cleaning methods, the error can be reduced in different levels during the solar wind simulation. Among the three divergence cleaning methods we used, the composite diffusive/Powell method can maintain divergence cleaning constraint better to a certain extent, and the relative magnetic field divergence error can be controlled at the order of 10^-9. Although these numerical simulations are performed for the background solar corona, these methods are also suitable for the simulation of CME initiation and propagation.

中文翻译：

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3D COIN-TVD MHD模型中发散清洁和日冕加热/加速方法的数值研究

在日冕数值模拟中，日冕加热/加速和磁发散清洁技术非常重要。近年来发展起来的日冕-行星际总变差（COIN-TVD）磁流体动力学（MHD）模型可以有效地实现日冕-行星际三维（3D）太阳风模拟。在本文中，我们使用 COIN-TVD MHD 模型专注于 3D 日冕太阳风模拟。为了模拟日冕区太阳风的加热和加速，对模型中的体积加热项进行了有效改进。然后，讨论了减少∇⋅B约束误差的不同方法对日冕太阳风结构的影响。在这里，我们选择 Carrington Rotation (CR) 2199 作为研究案例，并尝试使用3D COIN-TVD MHD模型对不同的磁发散清洁方法，包括扩散法、鲍威尔法和复合扩散/鲍威尔法的模拟结果进行比较。我们的模拟结果表明，采用不同的磁发散清洁方法，太阳风模拟过程中的误差可以不同程度地降低。在我们使用的三种发散清洁方法中，复合扩散/鲍威尔方法可以在一定程度上更好地保持发散清洁约束，相对磁场发散误差可以控制在10^-9的数量级。虽然这些数值模拟是针对背景日冕进行的，但这些方法也适用于 CME 启动和传播的模拟。