JAXA Supercomputer System Annual Report (April 2018-March 2019)

Study on dynamic instability of a reentry capsule at transonic speed
Report Number: R18ETET12
Subject Category: Skills Acquisition System
URL: https://www.jss.jaxa.jp/en/ar/e2018/9169/
Responsible Representative
Takashi Takahashi (Aeronautical Technology Directorate)
Contact Information
Aeronautical Technology Directorate, Numerical Simulation Research Unit (ohmichi.yuya@jaxa.jp)
Members
Kenji Kobayashi
Abstract
Typical blunt bodies often show dynamic instability in subsonic and transonic regimes because of unsteady
aerodynamic forces driven by complicate wake structures. In this study, we numerically simulated the flowfieldaround the capsule under the forced pitch oscillation motion, to investigate the flow structure around the oscillating
capsule. Then, we applied the proper orthogonal decomposition (POD) to the obtained unsteady flowfield data.
Reasons for using JSS2
Large computational cost is required to simulate the unsteady wake of an reentry capsule.
Achievements of the YearThe unsteady flow around the reentry capsule was obtained by a detached eddy simulation. Figure 1 shows acomparison of the pitching moment history between experiment and the present numerical results. The amplitudeof the moment coefficient shows good agreement with the experimental results. Then, by means of a properorthogonal decomposition (POD), we extracted the coherent structures (Figure 3) as the POD mode from theobtained flowfield data (Figure 2).

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JAXA Special Publication JAXA-SP-19-003E

Fig. 1: Pitching moment history. (Hashimoto, A., Murakami, K., Aoyama, T., Tagai,R., Koga, S., Nagai, S., “Dynamic Stability Analysis of a Reentry Lifting Capsulewith Detached Eddy Simulation,” AIAA paper 2016-0552, 2016.)

Fig. 2: Mach number distribution around the oscillating capsule.

Fig. 3: The spatial distribution of the POD mode. 2D contour shows the distributionof velocity in the x-direction at y = 0.
Publications- Oral Presentations
Kobayashi, K., Ohmichi, Y., Kanazaki, M., “Modal Decomposition Analysis of Subsonic Unsteady Flow Around
An Atmospheric Entry Capsule with Forced Oscillation,” AIAA Science and Technology Forum and Exposition
2019, San Diego, U.S.A, January 2019.
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JAXA Supercomputer System Annual Report (April 2018-March 2019)

Usage of JSS2

Computational Information
Process Parallelization Methods

MPI

Thread Parallelization Methods

OpenMPNumber of Processes

1024

Elapsed Time per Case

900 Hour (s)Resources Used
Fraction of Usage in Total Resources*1 (%): 0.62
Details
Computational Resources
System Name

Amount of Core Time(core x hours)

Fraction of Usage*2 (%)

SORA-MA

4,899,315.40

0.60

SORA-PP

48,405.94

0.39

SORA-LM

27,876.92

13.00

SORA-TPP

0.00

0.00

File System Resources
File System Name

Storage Assigned (GiB)

Fraction of Usage*2 (%)/home

238.420.25/data

42,480.49

0.75

/ltmp

976.560.08

Archiver Resources
Archiver Name

Storage Used (TiB)

J-SPACE

Fraction of Usage*2 (%)
17.33

0.61

*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.

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