Fugaku Supercomputer Enhances Flight Safety by Simulating Invisible Winds and Unveiling Clear Air Turbulence

by Hiroshi Tanaka
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aviation safety

Researchers from Nagoya University employ the powerful Fugaku supercomputer in Japan to simulate clear-air turbulence around Tokyo, offering valuable insights into the causes of turbulence and potentially advancing aviation safety.

Accurate Simulation of Air Turbulence using Fugaku Supercomputer

Nagoya University’s research team effectively harnesses the immense computational capabilities of Fugaku, Japan’s fastest supercomputer, to simulate clear-air turbulence in the Tokyo region. By cross-referencing their simulations with real flight data, they improve the accuracy of predictive models. Their study has been published in the journal Geophysical Research Letters.

Understanding Clear Air Turbulence (CAT)

Clear air turbulence (CAT) refers to the turbulent air movements experienced by aircraft, even on clear and sunny days when no visible clouds or atmospheric disturbances are present. Unlike turbulence associated with inclement weather, CAT poses a significant threat to aviation safety. Wind shear and atmospheric instability are believed to be the primary driving factors behind CAT, although its precise mechanisms remain incompletely understood.

CAT can lead to passenger and crew injuries, aircraft damage, and disruption of flight operations. Pilots rely on data from other aircraft, weather radar, and atmospheric models to anticipate and avoid turbulence. However, forecasting CAT is challenging due to the absence of visible indicators such as clouds or storms.

Large-Eddy Simulation (LES) and the Power Challenge

Scientists employ large-eddy simulation (LES), a computational fluid dynamics technique, to model turbulent flows and gain insights into CAT. However, LES presents a significant computational challenge due to the complexity of the interactions involved.

Overcoming Computational Challenges with Fugaku

To overcome these challenges, the Nagoya University research team utilized Fugaku, an exascale computing system housed at the Riken Center for Computational Science in Kobe, Japan. As the world’s second-fastest supercomputer, Fugaku provided the necessary computational power for the team to conduct highly detailed simulations of turbulence generation using high-resolution LES.

Revealing Turbulence Patterns in Tokyo

Dr. Ryoichi Yoshimura of Nagoya University and his colleagues, including Dr. Junshi Ito from Tohoku University, harnessed Fugaku’s immense computational power to conduct an ultra-high-resolution simulation of winter CAT above Haneda Airport in Tokyo. The simulation was triggered by low pressure and the presence of nearby mountains.

The team’s research uncovered that the disturbance in wind speed was caused by the collapse of the Kelvin-Helmholtz instability wave. This type of instability arises when two layers of air with different velocities interact, creating wave-like effects and fine vortices that induce turbulence.

Validation and Implications of the Research

The researchers validated their simulated vortices by comparing them with real-world data, utilizing abundant observational data available around Tokyo. Reports of turbulence and recorded shaking intensity from numerous airplanes flying over the airports were considered, along with atmospheric observations by a balloon near Tokyo. The validation process confirmed the accuracy of the calculations.

Dr. Yoshimura highlighted the importance of the research, stating that it deepens the understanding of turbulence generation principles and mechanisms through high-resolution simulations. Furthermore, it enables detailed investigations into the effects of turbulence on airplanes. With the knowledge gained, it becomes possible to adjust flight levels or avoid specific 3D regions known for active turbulence, improving routing decisions. Large-eddy simulation offers a promising avenue for more precise turbulence forecasts and real-time predictions, contributing to safer and smarter flying.

Reference: “Clear Air Turbulence Resolved by Numerical Weather Prediction Model Validated by Onboard and Virtual Flight Data” by R. Yoshimura, J. Ito, P. A. Schittenhelm, K. Suzuki, A. Yakeno, and S. Obayashi, 21 June 2023, Geophysical Research Letters.
DOI: 10.1029/2022GL101286

Frequently Asked Questions (FAQs) about aviation safety

What is clear air turbulence (CAT)?

Clear air turbulence (CAT) refers to turbulent air movements that can occur during a flight even on clear and sunny days without any visible clouds or atmospheric disturbances. It poses a significant threat to aviation safety.

How did the researchers utilize the Fugaku supercomputer?

The researchers from Nagoya University utilized the Fugaku supercomputer, Japan’s fastest supercomputer, to simulate clear-air turbulence around Tokyo. This high-performance computing system allowed them to conduct detailed simulations and enhance their understanding of turbulence generation.

What causes clear air turbulence?

Clear air turbulence is primarily driven by wind shear and atmospheric instability. The interaction between layers of air with different velocities, known as the Kelvin-Helmholtz instability wave, plays a significant role in creating turbulence.

How does the research enhance aviation safety?

By accurately simulating clear-air turbulence and validating their findings against real flight data, the researchers improve predictive models. This enhanced understanding of turbulence generation and its impact on aircraft can lead to more accurate forecasts and real-time predictions, allowing for safer flight operations and better avoidance of turbulent regions.

What is large-eddy simulation (LES)?

Large-eddy simulation (LES) is a computational fluid dynamics technique used to model turbulent flows. It helps scientists study and analyze complex interactions in turbulent air movements, such as clear air turbulence, providing valuable insights into its behavior and characteristics.

More about aviation safety

  • Geophysical Research Letters – The journal where the research study on clear air turbulence using Fugaku supercomputer was published.
  • Fugaku Supercomputer – Official website providing information about Fugaku, the supercomputer used in the research.
  • Nagoya University – Official website of Nagoya University, where the researchers are affiliated.
  • Kelvin-Helmholtz instability wave – Wikipedia page explaining the Kelvin-Helmholtz instability wave, which plays a role in clear air turbulence.
  • Computational Fluid Dynamics – Wikipedia page providing an overview of computational fluid dynamics, the technique used in the research to model turbulent flows.

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