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Experimental study on dynamics of coherent structures formed by inertial solid particles in three-dimensional
Masakazu Gotoda1, Denis E Melnikov2, Ichiro Ueno1
1Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, Japan.
Chaos (Woodbury, N.Y.)
|August 1, 2016
Summary
Solid particles form stable structures in oscillatory thermocapillary flows. Particle accumulation structure formation time depends on Stokes number, with two structure types observed.
Area of Science:
- Fluid dynamics
- Particle dynamics
- Thermocapillary effects
Background:
- Thermocapillary flows are driven by surface tension gradients due to temperature differences.
- Oscillatory flows can lead to complex particle behavior and structure formation.
- Understanding particle dynamics in such flows is crucial for various industrial and scientific applications.
Purpose of the Study:
- To investigate the dynamics of solid particles in periodic oscillatory thermocapillary-driven flows.
- To characterize the formation of particle accumulation structures (PASs).
- To determine the influence of particle properties and flow parameters on structure formation.
Main Methods:
- Experiments conducted under normal gravity using a non-isothermal liquid bridge filled with decane.
- Inertial particles of varying densities and sizes (0.75-75 μm) were used.
- Two image processing techniques were developed to measure the time required for PAS formation.
Main Results:
- Stable particle accumulation structures (PASs) were formed by inertial particles.
- PAS formation time increases as the Stokes number decreases.
- Two types of PASs, single-loop (SL-I) and double-loop (SL-II), were observed, with SL-II forming only with large or dense particles.
- Intermittently stable and asymmetric PASs were observed, alongside conventional symmetric structures.
- Particle collisions were found to disrupt PAS formation.
Conclusions:
- The Stokes number is a key parameter influencing PAS formation time.
- Particle size and density play critical roles in the type of PAS formed.
- Novel PAS behaviors, including intermittent stability and asymmetry, were identified.
- Inter-particle collisions negatively impact structure formation in these flows.
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