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Turbulence Unsteadiness Drives Extreme Clustering
F Zapata1,2, S Angriman1,2, A Ferran3,4
1Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Física, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
Physical Review Letters
|March 22, 2024
Summary
Turbulence unsteadiness significantly impacts particle clustering. This study reveals extreme clustering in natural flows due to unsteady turbulence, exceeding predictions from averaged effects.
Area of Science:
- Fluid dynamics
- Turbulence research
- Particle-laden flows
Background:
- Turbulence is often studied as a steady-state phenomenon.
- Particle clustering in turbulent flows is a key area of research.
- The influence of turbulence unsteadiness on particle behavior is not fully understood.
Purpose of the Study:
- To investigate the effect of unsteady turbulence on particle clustering.
- To identify correlations between flow parameters and particle cluster formation.
- To provide a dimensional argument for observed correlations.
Main Methods:
- Direct numerical simulations (DNS) were employed.
- A steady forcing generated an unsteady large-scale flow.
- Analysis focused on instantaneous turbulence parameters and particle clustering.
Main Results:
- Turbulence unsteadiness drastically affects turbulence parameters and particle clustering.
- Particle clustering correlates with the instantaneous Taylor-based flow Reynolds number.
- Particle clustering anticorrelates with the instantaneous turbulent energy dissipation constant.
Conclusions:
- Unsteadiness in turbulence is a critical factor in particle cluster formation.
- Extreme particle clustering can occur in natural unsteady flows.
- Observed clustering is more pronounced than predicted by averaged inertial turbulence effects.
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