Development of a new measure for fluid mixing and diffusion using Kolmogorov complexity

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06084
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Fluid engineering
• Research Institution: The University of Tokushima
• Principal Investigator: ICHIMIYA Masashi 徳島大学, 大学院社会産業理工学研究部(理工学域), 教授 (50193454)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 複雑さ / 乱流 / 混合層 / エントロピー

Outline of Final Research Achievements

To obtain the complexity of time sequence of fluid velocity signal, information entropy and permutation entropy were applied. They were applied into a mixing layer between jet and surrounding fluid as a typical example of fluid mixing process.
The information entropy of the fluctuating velocity increased monotonically within the turbulence transition processes in the mixing layer. Therefore, it was successfully used as the measure for the transition process. The permutation entropy of the fluctuating velocity varied complicatedly because of the increase of the fluctuating velocity and change of the manner of the fluctuation; from periodic to irregular fluctuation.

Free Research Field

工学

Academic Significance and Societal Importance of the Research Achievements

我が国ではエネルギー技術の一層の革新が求められている。このため発電効率のさらなる向上や空調設備のなお一層の効率化が重要である。また、原子力発電所事故での放射能汚染の拡散と予測に対しては、流体の混合拡散の重要性を改めて認識させた。
このため流体混合の目安つまり測度を客観的に、かつ実用的に使いやすい形で定める必要がある。本研究では新しい観点からコルモゴロフ複雑度に注目し、この混合や拡散の測度としての妥当性を明らかにした。