Particle-laden Flow

The solid particle-laden flows have been investigated as the important problems in fluid mechanics, which occurs frequently in nature and industrial applications. They are widely involved in various areas such as the atmospheric environment or pollution (toxic ultrafine dust in the air, volcano ash dispersion and so on), combustion of solid fuel, solar thermal reactors and fabrication facility for semiconductors.

Our main purposes are to determine the particle dispersion mechanism in the complex turbulent flow structures and to control the particle concentration. Thus, we are studying how to track the location and concentration of particle sources by 3D observation and control the particle cluster through geometric structures optimized for various types of flows. In addition, our lab researches into three-phase flows involving both bubbles and solid particles in the liquid phase.

1. Event camera

Three-dimensional particle diffusion experiment setup in jet flow

3D particle orientation and trajectory reconstruction

Position, tumbling rate and angular velocity of non-spherical particles

2. Granular flow

Experimental setup of granular flow rotating on a two-dimensional rotating drum

Raw image of 38um PMMA particles rotating with a speed of 7 rpm

Estimated velocity fields of granular bed using optical flow algorithm(left); Contour of individual particle velocities(right)

3. Step chamber

Experimental setup

Streamline on the time-averaged field

4. Particle-laden Jet

Experimental setup for particle-laden jet with the crossflow

Forces exerted on particles (vectors) & particle concentration (contours) when R ≈ 1 near the jet exit.

5. Particle leakage through exhalation valve on a face mask

Experimental setup for measurement of airflow and particle concentration with adaptive particle image velocimetry and high-speed imaging

Particle dispersion mechanism in the ejection state (Q=50 L/min) for the square(top) and circular(bottom) valve

Variation of the particle penetration by airflow rate for the square valve under cyclic flow

6. Negative pressure isolation room, NPIR

Ventilation system design (CFD)

Virus-laden breath aerosols are transported to the upper part of the room by the buoyant breath plume

Ventilation by short door openeing is essineital (discharging more than 20% aerosols)
Optimally designed indoor ventilation system discharge 99% virus aerosols in 3 min. (Note! common hospital environment takes more than 10-20min for ventilation)