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Study on dynamic instability of a reentry capsule at transonic speed

JAXA Supercomputer System Annual Report April 2020-March 2021

Report Number: R20ETET12

Subject Category: Skills Acquisition System

PDF available here

  • Responsible Representative: Takashi Takahashi(Aeronautical Technology Directorate)
  • Contact Information: Aeronautical Technology Directorate, Numerical Simulation Research Unit(ohmichi.yuya@jaxa.jp)
  • Members: Masato Harafuji

Abstract

It is known that atmospheric entry capsules exhibit dynamic instability during transonic to subsonic flight due to unsteadiness of wake dynamics. And, the possibility in which the fluid phenomenon of the specific frequency affects the dynamic instability is indicated. To investigate the wake dynamics, we numerically simulated flowfield around the normal flat plate, and we applied dynamic mode decomposition (DMD) to the obtained unsteady flowfield data.

Reference URL

N/A

Reasons and benefits of using JAXA Supercomputer System

Large calculation cost is required to simulate unsteady flow fields.

Achievements of the Year

A DMD analysis was performed on the numerical results for a normal flat plate at M=0.2. Figure 1 shows the collapse of the spanwise vortex at low frequencies obtained from the DMD. The wavelength of the spanwise unsteadiness is shown in Figure 2, and the characteristic structure of the low-frequency fluid phenomenon is extracted.

Annual Reoprt Figures for 2020

Fig.1: Vortex core structure behind a normal flat plate

 

Annual Reoprt Figures for 2020

Fig.2: Decay wavelength of vortex core

 

Publications

- Oral Presentations

Harafuji, M., Ohmichi, Y., Kanazaki, M., "Dynamic Mode Decomposition Analysis for Low-Frequency Phenomenon of the Wake behind a Normal Flat Plate," The 34th Computational Fluid Dynamics Symposium, Okinawa, December 2020.

Usage of JSS

Computational Information

  • Process Parallelization Methods: MPI
  • Thread Parallelization Methods: OpenMP
  • Number of Processes: 128
  • Elapsed Time per Case: 50 Hour(s)

Resources Used(JSS2)

 

Fraction of Usage in Total Resources*1(%): 0.09

 

Details

Please refer to System Configuration of JSS2 for the system configuration and major specifications of JSS2.

Computational Resources
System Name Amount of Core Time
(core x hours)
Fraction of Usage*2(%)
SORA-MA 306,613.12 0.06
SORA-PP 17,465.44 0.14
SORA-LM 1,309.47 0.77
SORA-TPP 0.00 0.00

 

File System Resources
File System Name Storage Assigned
(GiB)
Fraction of Usage*2(%)
/home 238.42 0.22
/data 42,480.49 0.82
/ltmp 976.56 0.08

 

Archiver Resources
Archiver Name Storage Used
(TiB)
Fraction of Usage*2(%)
J-SPACE 26.79 0.89

*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.

 

Resources Used(JSS3)

 

Fraction of Usage in Total Resources*1(%): 0.03

 

Details

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

Computational Resources
System Name Amount of Core Time
(core x hours)
Fraction of Usage*2(%)
TOKI-SORA 0.00 0.00
TOKI-RURI 32.04 0.00
TOKI-TRURI 0.00 0.00

 

File System Resources
File System Name Storage Assigned
(GiB)
Fraction of Usage*2(%)
/home 238.42 0.16
/data 42,480.49 0.71
/ssd 47.68 0.02

 

Archiver Resources
Archiver Name Storage Used
(TiB)
Fraction of Usage*2(%)
J-SPACE 26.79 0.89

*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.

JAXA Supercomputer System Annual Report April 2020-March 2021


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