Professor Peng Zhang - Dynamics of Droplet-Droplet Collision - Advancing Predictive Spray Combustion Models for a Net-Zero Future

IAS Visiting Fellow Professor Peng Zhang delivers a seminar on their research - 

Droplet-droplet collision is a fundamental process in both natural phenomena and industrial applications, serving as a microcosm of multi-scale fluid dynamics. This talk unravels the intricate physics governing collision outcomes—coalescence, bouncing, and separation—beginning with the canonical case of identical droplets. We highlight the interplay between macroscopic droplet kinematics, internal flow dynamics, and microscale interfacial interactions (e.g., rarefied gas films and van der Waals forces), which collectively define the system’s multi-physics behaviour. Expanding beyond symmetric collisions, we explore complex scenarios involving unequal-sized droplets, non-Newtonian fluids, and dissimilar droplets, alongside analogous jet-jet collisions. By synthesizing these insights, we bridge fundamental fluid dynamics with predictive spray combustion modeling, emphasizing how microscale collision physics can constrain macroscale combustion efficiency and emissions—particularly for low-carbon fuels. This work provides a framework to improve the accuracy of spray combustion simulations, supporting the development of cleaner combustion technologies.

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