Development of fast simulation tools for off-design aerodynamics

JAXA Supercomputer System Annual Report February 2025-January 2026

Report Number: R25EDA201J07

Subject Category: Aeronautical Technology

Responsible Representative: Kazuyuki Nakakita, Aeronarutical Technology Directorate, Fundamental research unit
Contact Information: Yoimi Kojima(kojima.yoimi@jaxa.jp)
Members: David Lusher, Sansica Andrea, Masashi Kanamori, Kenji Hayashi, Yoimi Kojima

Abstract

Under off-design flight conditions, where an aircraft deviates from its steady operational state, the aircraft geometry becomes more complex and unsteady phenomena tend to arise, leading to a significant increase in the computational scale of fluid simulations. In this project, we aim to accelerate numerical simulations under off-design flight conditions by improving the speed and efficiency of CFD codes.

Reference URL

N/A

Reasons and benefits of using JAXA Supercomputer System

In numerical simulations under typical off-design flight conditions, large-scale computational grids with hundreds of millions or more grid points are required. Consequently, the demands for computational resources and storage at each stage of the simulation (preprocessing, main computation, and postprocessing) become extremely high, making research and development leveraging supercomputers indispensable.

Achievements of the Year

For preprocessing computational grids on the order of several to tens of billions of cells required for off-design numerical simulations, it was anticipated that existing solvers would require more than 100 hours of processing time. By offloading part of the processing to GPUs, we achieved significant acceleration and reduced the runtime to a practical level (approximately 8 hours). As a result, large-scale grid-based numerical simulations can now be performed within a realistic time frame.

Fig.1: Workflow of off-design numerical simulations and the effect of preprocessing acceleration. While preprocessing previously required more than 100 hours, GPU acceleration reduced it to approximately 8 hours, enabling large-scale computations within a practical time frame.

Publications

N/A

Usage of JSS

Computational Information

Process Parallelization Methods: MPI
Thread Parallelization Methods: N/A
Number of Processes: 1 - 3456
Elapsed Time per Case: 24 Hour(s)

JSS3 Resources Used

Fraction of Usage in Total Resources*1(%): 0.72

Details

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

Computational Resources
System Name	CPU Resources Used (Core x Hours)	Fraction of Usage*2(%)
TOKI-SORA	15311091.21	0.69
TOKI-ST	4568.81	0.00
TOKI-GP	87232.24	1.41
TOKI-XM	57669.19	19.82
TOKI-LM	730.81	0.06
TOKI-TST	0.00	0.00
TOKI-TGP	0.00	0.00
TOKI-TLM	0.00	0.00

File System Resources
File System Name	Storage Assigned (GiB)	Fraction of Usage*2(%)
/home	0.00	0.00
/data and /data2	102400.00	0.67
/ssd	30720.00	1.87

Archiver Resources
Archiver Name	Storage Used (TiB)	Fraction of Usage*2(%)
J-SPACE	19.69	0.06

*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

ISV Software Licenses Resources
	ISV Software Licenses Used (Hours)	Fraction of Usage*2(%)
ISV Software Licenses (Total)	7.74	0.01

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