JAXA Supercomputer System Annual Report February 2025-January 2026

Report Number: R25EACA52

Subject Category: JSS Inter-University Research

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• Responsible Representative: Shinichiro Ogawa, Assistant professor, Osaka Metropolitan University
• Contact Information: Shinichiro Ogawa, Assistant professor, Osaka Metropolitan University(shinichiro.ogawa@omu.ac.jp)
• Members: Shinichiro Ogawa, Haruyuki Kato, Daisuke Sasaki

Abstract

In this project, a three-dimensional computational fluid dynamics (CFD) solver based on the Building-Cube Method (BCM) is developed to enable accurate and efficient analysis of complex flow fields within aerospace propulsion systems. Conventional CFD solvers face challenges such as difficulties in mesh generation for complex geometries, increased computational cost associated with high-order accuracy, and the complexity of pre- and post-processing procedures. In this study, BCM is applied to overcome these limitations, aiming to establish a computational framework that achieves both ease of applicability to complex geometries and high computational efficiency. The target applications include solid rocket motors and scramjet engines, with the objective of elucidating complex flow phenomena occurring within the engine internal flow fields. Furthermore, since these engines operate over a wide range of conditions from subsonic to supersonic regimes, the developed solver is employed to systematically investigate flow characteristics and performance across a broad operating envelope. Through this work, the establishment of a high-fidelity and computationally efficient numerical analysis methodology is expected to contribute to the advanced design and performance improvement of next-generation aerospace propulsion systems.

Reference URL

Please refer to https://www.omu.ac.jp/eng/ogawa/research/ .

Reasons and benefits of using JAXA Supercomputer System

In this study, three-dimensional computational fluid dynamics (CFD) simulations are performed to accurately capture the complex geometries and diverse flow phenomena within aerospace propulsion systems. These analyses involve extremely large computational scales and high computational costs. Therefore, the JAXA supercomputer, which provides a highly parallel computing environment, is utilized. This enables efficient execution of high-resolution simulations with large-scale computational grids, allowing detailed flow structures to be elucidated over a wide range of operating conditions within a practical computational time.

Achievements of the Year

In this study, a three-dimensional unsteady computational solver based on the Building-Cube Method (BCM) was newly developed, and numerical simulations of the internal flow field were performed for a scramjet combustor equipped with a cavity flame holder under a Mach 3 condition. The accuracy of the developed solver was validated by comparing the results with existing experimental and numerical data.

Furthermore, the effect of surface roughness in the nozzle expansion section of a solid rocket motor was investigated using the three-dimensional BCM solver. Numerical simulations were conducted for a simplified converging–diverging verification (CDV) nozzle under two operating conditions: subsonic flow and supersonic flow accompanied by a normal shock in the divergent section. The Mach number and static pressure distributions for the subsonic case and the supersonic case with a normal shock in the divergent section are shown in Figs. 1 and 2, respectively. The results indicate that, in the subsonic case, the influence of geometric deformation on the flow field is negligible. In contrast, for the supersonic flow with a normal shock in the divergent section, the deformation significantly shifts the shock location upstream by approximately 40 mm.

Fig.1: Comparison of Mach number distributions before and after nozzle deformation

Fig.2: Comparison of static pressure distributions before and after nozzle deformation

Publications

- Peer-reviewed papers

1) Shinichiro Ogawa, Kentaro Miyata, Shinichiro Ogawa, "Numerical investigation of flow dynamics and aerodynamics characteristics of cavity flameholders in divergent sections of scramjet combustors using building-cube method," CEAS Space Journal, 2025.

2) Shinichiro Ogawa, "Three-dimensional cold flow analysis of the effect of the nozzel cavity volume on the internal flowfiled in a solid rocket motor using the building-cube method," Fluid Dynamics Research, 57 (4), 2025.

- Oral Presentations

1) Shinichiro Ogawa Daisuke Sasaki, "Development of a numerical analysis method for internal flow fields in solid rocket motors using the Building-Cube Method," 2025 Fall Meeting of the Japan Explosives Society, November 2025.

2) Shinichiro Ogawa, Daisuke Sasaki, "Numerical Analysis of the Influence of Surface Roughness on the Internal Flow Field in the Expansion Section of a Rocket Nozzle," 43rd Aerospace Numerical Simulation Symposium, Jul 2025.

3) Haruyuki Kato, Kenta Tsukuda, Shinichiro Ogawa, Daisuke Sasaki, "Aerodynamic performance prediction of the CRM-HL using FaSTAR,"43rd Aerospace Numerical Simulation Symposium, Jul 2025.

Usage of JSS

Computational Information

• Process Parallelization Methods: N/A
• Thread Parallelization Methods: OpenMP
• Number of Processes: 1
• Elapsed Time per Case: 100 Hour(s)

JSS3 Resources Used

Fraction of Usage in Total Resources*1(%): 0.02

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