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Newsletter  2017.2  Index

Theme : "The Conference of Fluid Engineering Division"

  1.  Preface
    M.MOTOZAWA, T.HASHIMOTO, S.MATSUDA
  2. The Study of Turbulence in the 21st Century
    Shinichiro YANASE (Okayama University)
  3. Research on amorphous actuators utilizing liquid crystal flows
    Rinko MATSUDA, Tomohiro TSUJI, Shigeomi CHONO (Kochi University of Technology)
  4. Flow Structure of Hub-Corner Separation in a Stator Cascade of a Multi-Stage Transonic Axial Compressor
    Seishiro SAITO(Kyushu University)
  5. A levitating droplet over a moving surface
    Erina SAWAGUCHI, Kai HAMA, Yoshiyuki TAGAWA (Tokyo University of Agriculture and Technology)
  6. Innovative Cellulose Material Synthesis by Electrostatic Fibril Alignment
    Yusuke Takeda (Tohoku University), Christophe Brouzet, Nitesh Mittal, Fredrik Lundell (KTH Royal Institute of Technology, Sweden), Hidemasa Takana (Tohoku University)
  7. Developing “Dream Strider”, a machine for the removal of floating materials on the water surface
    Kota TSUBONE, Yo MUNETA (Hiroshima Kokutaiji Senior High School)
  8. The Dreams of Flow Contest
    Haruka YAMAUCHI (Meisei University)

 

The Study of Turbulence in the 21st Century


Shinichiro YANASE
Okayama University

 

Abstract

Turbulence is an eternal target of fluid mechanics. In the end of the 20th century, the numerical simulation of turbulence was started. The famous milestone was Stanford Conference held in 1980-1981. However, the conclusion showed the prematurity of computational fluid dynamics (CFD) mainly due to insufficient computer power. After the conference, a rapid development of the super computer started ironically and CFD of turbulence became popular. But the research is limited in the academic field far from manufacturing industries. In the 21st century, on the other hand, the popularization of turbulence calculation has occurred because of spreading of low coat but high performance PCs and CFD tools in which turbulence models are implemented. Now CFD of turbulence has attained the stage useful even for small manufacturing companies. In this paper, one example of the turbulence calculation using a CFD tool is presented. Turbulence of functional fluids has attracting much interest because of its utility in engineering applications. Among them, turbulence including microbubbles has a lot of physically unique properties and the drag reduction of the pipe flow is observed, which is addressed based on the author’s experimental results. Recently Kolmogorov’s inertial subrange needs reconsideration on its existence condition and ubiquitousness, which needs further study not only theoretically but also experimentally. Finally, the applicability of the probability theory is discussed referring the book of probability and stochastic processes recently written by the author. Though turbulence is probabilistic phenomena, the application of probability theory has not been made much progress these decades. However this way of study is most likely to proceed with advanced technologies of turbulence measurement and advanced mathematics.

 

Key words

Turbulence, Turbulence Model, Microbubble, Kolmogorov, 21st century

 

Figures


Fig.1 Q-value representation of the coherentvortices beneath the rotating disk.


Fig.2 Energy spectrum and enstrophy spectrum


Fig.3 (a) PDF of the velocity field.


Fig.3 (b) PDF of the time derivative of the velocity field.

 

References

Batchelor, G. K. , “The Theory of Homogeneous Turbulence”, Cambridge Univ. Press (1953).
Kline, S. J. and Lilley, G. M., Correspondent Report on the Initial Meeting, Held September 3–6, 1980, of the 1980–1981
AFOSR-HTTM-Stanford Conference on Complex Turbulent Flows: Comparison of Computation and Experiment, Trans. ASME J. Fluids Eng., 103 (1981), pp.184-188.
Kouchi, T.,Fukuda, S.,Nakano, Y.,Shimizu, Y.,Nagata, Y. and Yanase, S.,Periodical structure of vortices in a semiconductor single wafer spin cleaner,Transactions of the JSME (in Japanese), Vol. 81, No.829 (2015), No.15-00273.
Monin, A. S. and Yaglom, A. M., “Statistical Fluid Mechanics I, II”, M. I. T. Press (1971).
Vassilicos, J. C., Dissipation in Turbulent Flows, Ann. Rev. Fluid Mech., Vol. 47 (2015), pp.95-114.
Yanase, S.,AFOSR-HTTM-Stanford Conference on Complex Turbulent Flows,Butsuri,Vol. 37 (1982), 246-248 (in Japanese).
Yanase, S.,Matsuura, K.,Recent Development of the Micro-bubble Science,Nagare,Vol. 34 (2015), 355-362 (in Japanese).
Yanase, S.,“Probability and Stochastic Processes”,Morikita Pub. Co. (2015) (in Japanese).

Last update: 22.2.2017