JAXA Supercomputer System Annual Report April 2016-March 2017

Report Number: R16E0043

• Responsible Representative: Kiyoshi Kuramoro(Hokkaido University)
• Contact Information: Youhei Sasaki(uwabami@math.kyoto-u.ac.jp)
• Members: Youhei Sasaki, Jun Kimura, Kiyoshi Kuramoro
• Subject Category: Space(Space philosophy)

Abstract

We will clarify the current internal state of Mercury and the evolution by numerical calculations of the internal structure and the intrinsic magnetic field generation and comparing with the data obtained from observations.

Goal

Numerical analysis of Mercury's thermal history, evolution of the metallic core, intrinsic magnetic field generation were carried out in consideration of the possibility that the composition of the mantle and the core differed from the Earth. The origin of Mercury's intrinsic magnetic field was investigated closely related to Mercury's material science characteristics and its impact on the thermal history of 4.5 billion years. It will be contributes to an integrated interpretation of knowledge obtained from Messenger and new exploration data will be obtained from Bepi Colombo.

Objective

Numerical calculation of Mercury's thermal history and core cooling history were carried out with the mantle viscosity and core melting characteristics predicted from the estimated composition in order to show the current physical state and its compositional dependency of the mantle and the core. And numerical calculation of the Mercury's dynamo with the structure of the core, thermal and buoyant flux obtained from thermal history calculation were carried out. By clarifying how the strength and shape of the magnetic field depends the heat/buoyancy flux and the thickness of the liquid core, interpret various new exploration data such and contribute to constrain the internal physical condition and thermal history of 4.5 billion years.

References and Links

N/A

Use of the Supercomputer

We use super computer for systematic numerical calculation of the mantle convection and dynamo action in rotating spherical shell and analysis of these results.

Necessity of the Supercomputer

Because the mantle convection and the dynamo action in the rotating spherical shell are strong nonlinear systems, systematic large-scale numerical experiments are necessary in order to understanding these results. In addition, large computational resources is required for analysis of the results obtained from these numerical experiments.

Achievements of the Year

Continuing from the last fiscal year, we improve performance, especially parallel efficiency of the numerical model of MHD in rotating spherical shell. In order to carry out large scale calculation efficiently, we revised the algorithms for parallel computation and made full modifications to the software programs. As a result, although parallelization efficiency has been greatly improved, it was difficult to carry out scientific meaningful calculations within the deadline.

Publications

Peer-reviewed articles

1) Takehiro, S-I., Sasaki, Y., 2017: Penetration of steady fluid motions into an outer stable layer excited by MHD thermal convection in rotating spherical shells, Physics of the Earth and Planetary Interiors, doi: 10.1016/j.pepi.2017.03.001

2) Kamata, S., Kimura, J., Matsumoto, K., Nimmo, F., Kuramoto, K., & Namiki, N. (2016). Tidal deformation of Ganymede: Sensitivity of Love numbers on the interior structure. Journal of Geophysical Research: Planets, 121, 1362-1375

Presentations

1) Sasaki, Y., Takehiro, S., Ishiwatari, M., Yamada, M., 2016: Critical mode of anelastic thermal convection in a rotating spherical shell depends on radial distribution of thermal diffusivity, SEDI The 15th Symposium, Nantes, France.

2) Sasaki, Y., Takehiro, S., Ishiwatari, M., Yamada, M., 2016: Critical mode of anelastic thermal convection in a rotating spherical shell depends on radial distribution of thermal diffusivity, SEDI The 15th Symposium, Nantes, France.

Computational Information

• Parallelization Methods: Hybrid Parallelization
• Process Parallelization Methods: MPI
• Thread Parallelization Methods: OpenMP
• Number of Processes: N/A
• Number of Threads per Process: N/A
• Number of Nodes Used: N/A
• Elapsed Time per Case (Hours): N/A
• Number of Cases: N/A

Resources Used

Total Amount of Virtual Cost(Yen): 58,467

Breakdown List by Resources

Note: Virtual Cost=amount of cost, using the unit price list of JAXA Facility Utilization program(2016)

JAXA Supercomputer System Annual Report April 2016-March 2017