Voronoi-based analysis of clustering dynamics in experimental volcanic ash clouds

Area of Science:

• Geosciences
• Atmospheric Science
• Fluid Dynamics

Background:

• Explosive volcanic eruptions release ash, posing risks to aviation and public health.
• Current ash dispersal models often neglect evolving atmospheric ash distributions and particle interactions.

Purpose of the Study:

• To experimentally quantify particle clustering in volcanic ash columns.
• To investigate how particle size distribution and volume fraction influence clustering dynamics.
• To assess the impact of clustering on ash transport, aggregation, and settling.

Main Methods:

• Controlled laboratory experiments simulating ash columns.
• High-speed laser-illuminated videography for particle tracking.
• Voronoi tessellation analysis to quantify preferential concentration.

Main Results:

• Particle-driven convection intensifies with decreasing particle size.
• Varying particle volume fraction significantly modulates clustering across various sizes.
• Clustering leads to inhomogeneous ash distributions, enhanced particle interactions, and altered settling velocities.

Conclusions:

• Turbulence-driven clustering significantly impacts volcanic ash dynamics.
• Observed clustering challenges traditional assumptions about particle size and settling velocity.
• Incorporating these findings into dispersal models will improve ash forecast accuracy.