Simulation and Visualization of MHD Relaxation in a Sphere

2021 Fiscal Year Final Research Report

• Project/Area Number: 17H02998
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Plasma science
• Research Institution: Kobe University
• Principal Investigator: Kageyama Akira 神戸大学, システム情報学研究科, 教授 (20260052)
• Project Period (FY): 2017-04-01 – 2022-03-31
• Keywords: 自己組織化 / 磁気流体力学 / 可視化

Outline of Final Research Achievements

We found that there are two types of relaxed states of magnetohydrodynamics in a sphere in which flow and magnetic fields coexist. One is a state in which the magnetic and flow fields are almost parallel. A typical example of this state is the so-called twist flow. The other is a state in which the flow and magnetic field have different structures and distributions. In this state, the energy of the flow and the magnetic field is concentrated in opposite hemispheres, and the jet-like flow and the tension in the magnetic field generated by the flow maintain a quasi-steady state while supplying energy in a complementary manner. The visualization method developed to analyze these computations was established as a new visualization method with versatility, named 4D Street View. A dedicated library and video player to realize 4D Street View were also successfully developed and widely released to the public along with sample data.

Free Research Field

計算科学

Academic Significance and Societal Importance of the Research Achievements

余分なエネルギーをもつプラズマは熱平衡状態に至るまでの長い時間、準定常状態を保つ。そこにみられる様々な構造は多くの研究者の興味をひきつけてきた。磁場のみ（つまり流れのない）準定常状態への緩和について主に調べられてきたこれまでの研究を大きく拡張し、流れと磁場が共存した緩和過程について明らかにしたという点に本研究の学問的な意義がある。また、この研究で開発した4次元ストリートビュー手法は球内部の磁気流体シミュレーションに限らず様々な形状や種類の大規模シミュレーションに適用できる汎用性をもつことが確認された。この手法とオープンソースとして公開した基本ツールは幅広い研究開発に活用されることが期待できる。