JAXA Supercomputer System Annual Report February 2025-January 2026

Report Number: R25EDA201G20

Subject Category: Aeronautical Technology

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• Responsible Representative: Kazuyuki Nakakita, Aviation Technology Directorate, Fundamental Aeronautics Research Unit
• Contact Information: Shingo Matsuyama(matsuyama.shingo@jaxa.jp)
• Members: Shingo Matsuyama, Keisuke Fujii

Abstract

Strong shock waves are generated around a flying object at hypersonic speeds, and the high-temperature gas compressed by the shock waves causes strong heat transfer to the hypersonic vehicle. The objective of this research is to establish a technique to reproduce such a flow field around a hypersonic vehicle by CFD and to accurately evaluate the aerodynamics and heating applied to the vechicle.

Reference URL

N/A

Reasons and benefits of using JAXA Supercomputer System

The flight conditions of hypersonic vehicles often have high Reynolds numbers, which necessitates the evaluation of turbulent heating. Since this study aims to evaluate turbulent heating with high accuracy using Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES), a three-dimensional unsteady analysis is inevitably required. The computational cost of such a large-scale three-dimensional analysis is very high, and analysis using a supercomputer is essential.

Achievements of the Year

To understand the mechanism of boundary layer turbulent transition observed during the S-520-RD1 flight experiment, we performed DNS simulations for actual flight conditions. In DNS simulations of boundary layer transition, the treatment of initial disturbances is crucial. In this analysis, we assumed that disturbances were generated by protrusions on the vehicle surface caused by a gap filler material between the panels. DNS simulations were performed on a configuration with protruding gap fillers, confirming that turbulent transition occurs as a result of the disturbances caused by these protrusions (Figs. 1 and 2). Furthermore, simulations performed for various flight conditions roughly reproduced the tendencies observed for the heat flux data obtained in the flight experiment (Fig. 3).

Fig.1: Results of DNS analysis of S-520-RD1 flight experiment (Mach 5.8). The boundary layer turbulence transition caused by the protruding gap filler is shown using iso-surfaces of the second invariant of the velocity gradient tensor (colored by Mach number). The black circle indicates the location of heat flux sensor.

Fig.2: Results of DNS analysis of S-520-RD1 flight experiment (Mach 5.8). Instantaneous wall heat flux distribution is shown. The black circle indicates the location of heat flux sensor.

Fig.3: Comparison of heat flux values obtained from DNS with flight data.

Publications

- Non peer-reviewed papers

1) Shingo Matsuyama, "Post-flight Analysis of S-520-RD1 Flight Experiment Data", Proceedings of the 57th Fluid Dynamics Conference / the 43rd Aerospace Numerical Simulation Symposium, SP-25-010, p. 95-100, 2026.

- Oral Presentations

1) Shingo Matsuyama, "Post-flight Analysis of S-520-RD1 Flight Experiment Data", the 57th Fluid Dynamics Conference / the 43rd Aerospace Numerical Simulation Symposium, 2025.

2) Shingo Matsuyama, "DNS of Turbulent Transition in the Hypersonic Boundary Layer during S-520-RD1 Flight Experiment", the JSASS North Branch Annual Meeting 2026 and the 7th Symposium on Reusable Space Transportation Vehicles, 2026.

Usage of JSS

Computational Information

• Process Parallelization Methods: MPI
• Thread Parallelization Methods: OpenMP
• Number of Processes: 64 - 284
• Elapsed Time per Case: 80 Hour(s)

JSS3 Resources Used

Fraction of Usage in Total Resources*1(%): 2.59

Details

Please refer to System Configuration of JSS3 for the system configuration and major specifications of JSS3.

*1: Fraction of Usage in Total Resources: Weighted average of three resource types (Computing, File System, and Archiver).

*2: Fraction of Usage：Percentage of usage relative to each resource used in one year.

ISV Software Licenses Used

*2: Fraction of Usage：Percentage of usage relative to each resource used in one year.

JAXA Supercomputer System Annual Report February 2025-January 2026