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Universality of small scale turbulence.
Ch Renner1, J Peinke, R Friedrich
1Fachbereich Physik, Carl-von-Ossietzky Universität Oldenburg, D-26111 Oldenburg, Germany.
Physical Review Letters
|September 13, 2002
Summary
Turbulence universality is challenged by new Markov process methods. Results show small-scale turbulence is far from universal, even at high Reynolds numbers (Re).
Area of Science:
- Fluid dynamics
- Turbulence research
- Statistical physics
Background:
- The universality of small-scale turbulence is a long-standing hypothesis in fluid dynamics.
- Traditional analysis relies on structure functions and probability density functions of velocity increments.
- High Reynolds numbers are crucial for observing universal turbulent behavior.
Purpose of the Study:
- To investigate the proposed universality of small-scale turbulence.
- To explore a novel analytical method for characterizing turbulence.
- To assess turbulent behavior across a wide range of Reynolds numbers.
Main Methods:
- Measurements were conducted in a cryogenic free jet.
- Reynolds numbers (Re) varied from 8500 to 10^6 (max R(lambda) approx 1200).
- A new method based on Markov process theory was employed, analyzing joint probabilities of velocity increments at multiple scales, replacing traditional structure functions and probability density functions.
Main Results:
- The study utilized a novel Markov process-based method for turbulence analysis.
- Results indicate a significant deviation from universal behavior in small-scale turbulence.
- This deviation was observed even at high Reynolds numbers (R(lambda) > 1000).
Conclusions:
- The findings challenge the proposed universality of small-scale turbulence.
- The Markov process method provides a more comprehensive characterization of turbulence.
- Turbulence in cryogenic free jets does not exhibit universal characteristics under the tested conditions.