JAXA Supercomputer System Annual Report February 2025-January 2026

Report Number: R25EDG20104

Subject Category: Research and Development

PDF (to be added)

• Responsible Representative: Seiji Tsutsumi, RInsertHereD Manager, Research and Development Directorate, Research Unit III
• Contact Information: Seiji Tsutsumi(tsutsumi.seiji@jaxa.jp)
• Members: Masaharu Abe, Takanori Haga, Hiroyuki Ito, Yasuhito Okano, Seiji Tsutsumi

Abstract

This study focuses on predicting supersonic jet noise generated during the landing of a reusable rocket using computational fluid dynamics (CFD). The project aims to predict aerodynamic noise induced by the engine exhaust jet during reusable rocket landing. As part of a collaborative research effort with CNES, we discuss CFD modeling and the underlying acoustic generation mechanisms using experimental data provided by both JAXA and CNES.

Reference URL

N/A

Reasons and benefits of using JAXA Supercomputer System

In this study, we utilized a supercomputer, a large-scale computational resource, to achieve high‑fidelity predictions of the supersonic jet noise generated during the landing of a reusable rocket. Around the engine exhaust jet during landing, strong shock structures and unsteady turbulent flows interact in a highly complex manner, requiring high spatial and temporal resolutions that are difficult to attain with conventional computational environments. Therefore, we employed the large‑scale parallel computing capabilities of the supercomputer to perform detailed Large‑Eddy Simulations (LES) and acoustic analyses. Furthermore, extensive parametric computations were essential for validating the modeling methods and elucidating the acoustic generation mechanisms using experimental data provided by CNES and JAXA, making the use of the supercomputer indispensable.

Achievements of the Year

We conducted our analysis using LS‑Flow‑HO, JAXA’s in‑house CFD code. As an initial step, a free‑jet simulation was performed to prepare for the CFD analysis of the test cases provided by JAXA, allowing us to verify the computational conditions and modeling approaches. We are currently carrying out simulations that apply the Synthetic Eddy Method to the nozzle‑exit boundary condition, in order to validate the treatment of inflow turbulence. In the next phase, we plan to analyze one of the JAXA test cases in which a ground‑mockup impact plate is located at a downstream position of 1D from the nozzle exit, where D denotes the nozzle‑exit diameter. In addition, a wall model will be employed to represent the turbulent boundary layer forming on the plate surface. The computational grid required for these analyses has already been generated, and we will proceed to detailed simulations accordingly.

Publications

N/A

Usage of JSS

Computational Information

• Process Parallelization Methods: MPI
• Thread Parallelization Methods: OpenMP
• Number of Processes: 512
• Elapsed Time per Case: 871.5 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