JAXA Supercomputer System Annual Report April 2016-March 2017

Report Number: R16E0049

• Responsible Representative: Naofumi Ohnishi(Tohoku University)
• Contact Information: Naofumi Ohnishi(ohnishi@rhd.mech.tohoku.ac.jp)
• Members: Hiroaki Tatematsu, Naofumi Ohnishi
• Subject Category: Space(Spacecraft)

Abstract

Unstable modes were obtained by conducting dynamic mode decomposition to field data calculated by numerical simulation of hypersonic flow around a sharp cone which was used in past experiment. The characteristic mode was extracted and had the similar structure to the second mode, which is considered as an unstable mode. Moreover, different frequencies were obtained between the modes in upstream and downstream, suggesting that a mode transfer may occur until a position at which the turbulent transition was observed in the experiment.

Goal

Prediction of turbulent transition in a boundary layer is required for an accurate estimation of heat load in a hypersonic flight. A goal of this study is clarifying mechanisms inducing the turbulent transition and growth of unsteady modes in the hypersonic boundary layer based on results of computational fluid dynamics.

Objective

Unsteady modes are extracted by dynamic mode decomposition method from numerical simulations of hypersonic flow around a sharp cone object, and features and development of the unsteady modes are discussed by comparing with experimental data.

References and Links

N/A

Use of the Supercomputer

Computational fluid dynamics simulations were conducted for high-resolution and long-term conditions.

Necessity of the Supercomputer

A high-resolution numerical simulation is required for extracting growth of the unstable modes with small numerical disturbances. A physically long-term simulation is also needed for capturing the low-frequency phenomenon.

Achievements of the Year

Characteristic frequencies were found (Fig. 1) in time history of wall pressure by conducting numerical simulation of hypersonic flow around a sharp cone which was used in past experiment. The characteristic mode was extracted (Fig. 2) by dynamic mode decomposition from the obtained flow data and had the similar structure to the second mode, which is considered as an unstable mode.

Fig.1:Wall pressure variation around a sharp cone

Fig.2:Unstable pressure mode obtained by the dynamic mode decomposition

Publications

Non peer-reviewed articles

1) Hiroki Tatematsu, Yousuke Ogino, Naofumi Ohnishi, and Hideyuki Tanno, ‘Analysis of Unstable Mode Structures in Hypersonic Boundary Layer,’ AIAA Paper 2017-1695, (2017).

Presentations

1) Hiroki Tatematsu, Yousuke Ogino, Naofumi Ohnishi, and Hideyuki Tanno, ‘Analysis of Unstable Mode Structures in Hypersonic Boundary Layer,’ 55th AIAA Aerospace Sciences Meeting, AIAA SciTech Forum, Grapevine, Texas, January 9—13, 2017.

Computational Information

• Parallelization Methods: Process Parallelization
• Process Parallelization Methods: MPI
• Thread Parallelization Methods: n/a
• Number of Processes: 512
• Number of Threads per Process: 1
• Number of Nodes Used: 16
• Elapsed Time per Case (Hours): 96
• Number of Cases: 4

Resources Used

Total Amount of Virtual Cost(Yen): 1,924,169

Breakdown List by Resources

Note: Virtual Cost=amount of cost, using the unit price list of JAXA Facility Utilization program(2016)

JAXA Supercomputer System Annual Report April 2016-March 2017