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Transition to Turbulence in Particle Laden Flows
Nishchal Agrawal1, George H Choueiri1, Björn Hof1
1Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria.
Physical Review Letters
|April 6, 2019
Summary
Adding particles to fluids creates new flow regimes. At high concentrations, a globally fluctuating state emerges, competing with the known transition to turbulent puffs.
Area of Science:
- Fluid dynamics
- Turbulence studies
- Particle-laden flows
Background:
- Suspended particles modify fluid properties, influencing laminar-to-turbulent flow transitions.
- Previous research documented particle effects on subcritical (hysteretic) transitions to turbulent puffs.
Purpose of the Study:
- Investigate new flow regimes in particle-laden fluids.
- Characterize the impact of increasing particle concentration on flow dynamics.
Main Methods:
- Experimental or computational fluid dynamics approach (details not specified in abstract).
- Analysis of flow regimes under varying particle concentrations.
- Observation of transitions from laminar to turbulent states.
Main Results:
- A supercritical (continuous) transition to a globally fluctuating state occurs with increasing particle concentration.
- The conventional Newtonian-type transition to turbulent puffs is delayed to higher Reynolds numbers.
- At high concentrations, only the globally fluctuating state persists.
- Three distinct flow regimes identified: Newtonian-type turbulence, particle-induced global fluctuations, and a coexistence state.
Conclusions:
- Particle-laden flows exhibit complex dynamics driven by competing instabilities.
- Flow behavior transitions from Newtonian-like turbulence to a particle-dominated fluctuating state as concentration increases.
- The study reveals a richer phase diagram for particle-laden flows than previously understood.
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