JAXA Supercomputer System Annual Report February 2025-January 2026

Report Number: R25EDA201A32

Subject Category: Aeronautical Technology

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• Responsible Representative: Hiroyuki Abe, Aviation Technology Directorate, Fundamental Aeronautics Research Unit
• Contact Information: Takashi Ozawa(ozawa.takashi@jaxa.jp)
• Members: Yuki Ide, Shingo Matsuyama, Takashi Ozawa, Toshiyuki Suzuki

Abstract

In this study, we try to enhance physical models for high temperature gas and numerical simulation method to accurately predict heating and aerodynamic characteristics at atmospheric entry. We aim to develop high fidelity simulation tool by demonstrating improvement of prediction accuracy by comparing experimental data and simulation results with the newly proposed model and method. In this year, we focus on the analysis of hypersonic flows inside a light-gas-gun and around capsules, attitude instability analysis for sample return capsules in addition to rarefied gas dynamics. Additionally, numerical prediction tools for laminar-turbulent transition in hypersonic boundary layers are developed.

Reference URL

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Reasons and benefits of using JAXA Supercomputer System

In order to evaluate uncertainties and dependence on nonequilibrium thermochemical models, configurations, and freestream conditions, supercomputer has been used to perform a large number of CFD and DSMC runs by changing physical models, configurations, and flow conditions.

Achievements of the Year

In this study, we first carried out DSMC computations to study intake performance (see Fig. 1) for air breathing ion engine (ABIE) flight tests. In addition, because the effect of micro-structured surfaces on aerodynamics and pressure is not well-known in rarefied flow regime, we conducted DSMC computations to study micro-structured surface dependence (see Fig. 2) in order to compare with HRWT (Hypersonic Rarefied Wind Tunnel) measured data. With respect to the stability of boundary layers, we investigated the effects of primary crossflow vortices on non-modal energy gains and resulting localization area of optimal perturbations in a three-dimensional compressible flow (see Fig. 3). Furthermore, to clarify the mechanism of hypersonic boundary layer transition during the S-520-RD1 flight experiment, DNS analysis was performed at Mach 5.8 on a configuration with protruding gap filler on the vehicle surface (see Fig. 4).

Fig.1: Distribution of density compression ratio inside and around an intake in a very low earth orbit

Fig.2: Comparison of normalized pressure distributions inside wind tunnel models between without (top) and with (bottom) micro-structured surfaces.

Fig.3: Energy gain and spatial localization region of optimal perturbations in a supersonic three-dimensional boundary layer

Fig.4: Boundary layer transition at Mach 5.8 caused by a protruding gap filler (iso-surface of the second invariant of the velocity gradient tensor colored by Mach number)

Publications

- Peer-reviewed papers

1) Rarefied Gas Dynamics, Proceedings of the 33rd International Symposium, Springer Aerospace Technology, 2026

2) Non-modal secondary growth in a boundary layer modulated by primary crossflow vortices, Physics of Fluids 37, 054103 (2025)

- 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) Ryunosuke Endo et al., "Optimization of the ABIE Intake Model for Pressure Measurement in Rarefied Gas Flow", 35th International Symposium on Space Technology and Science, 2025.

2) Ryunosuke Endo et al., "Evaluation of Pressure Distribution Effects of Micro-Structured Surfaces in Hypersonic Rarefied Wind Tunnel Environments", 69th Space Science and Technology Conference, 2025.

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

4) 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: 366 - 2928
• Elapsed Time per Case: 24 Hour(s)

JSS3 Resources Used

Fraction of Usage in Total Resources*1(%): 1.68

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