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Mixing in two-dimensional shear flow with smooth fluctuations
Nikolay A Ivchenko1, Vladimir V Lebedev1, Sergey S Vergeles1
1<a href="https://ror.org/00z65ng94">Landau Institute for Theoretical Physics</a>, Russian Academy of Sciences, 1-A Akademika Semenova av., 142432 Chernogolovka, Russia and <a href="https://ror.org/055f7t516">National Research University Higher School of Economics</a>, Faculty of Physics, Myasnitskaya 20, 101000 Moscow, Russia.
Physical Review. E
|August 20, 2024
Summary
This study explores passive scalar mixing in chaotic shear flows, revealing strong intermittency. Chaotic flow enhances mixing through intensified stirring, impacting statistical properties.
Area of Science:
- Fluid dynamics
- Turbulence theory
- Statistical mechanics
Background:
- Passive scalar mixing is crucial in various natural and engineered systems.
- Understanding mixing dynamics in chaotic flows is essential for predicting field evolution.
- Previous models often simplified the complex interplay between shear and fluctuations.
Purpose of the Study:
- To investigate the statistical properties of passive scalar fields in 2D shear flows with random fluctuations.
- To model scalar mixing in scenarios like 2D turbulence and microchannel elastic turbulence.
- To analyze intermittency in both decaying and continuously forced scalar variance cases.
Main Methods:
- Analysis of a 2D flow model where shear dominates smooth fluctuations.
- Examination of scalar variance dynamics under decaying and continuous forcing.
- Calculation of single-point moments and correlation functions.
- Focus on models with time-short correlated fluctuations.
Main Results:
- Chaotic flow variations significantly intensify scalar field mixing.
- The dynamics exhibit strong intermittency, quantifiable through moments and correlations.
- General qualitative properties of the pair correlation function were determined.
- Quantitative results were obtained for short-correlated fluctuation models.
Conclusions:
- Chaotic shear flows provide an effective mechanism for rapid passive scalar mixing.
- Intermittency is a key characteristic of scalar field dynamics in these flows.
- The study provides valuable insights into scalar mixing relevant to turbulence and microfluidics.
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