Each day, individuals across the globe inhale millions of microscopic particles, ranging from soot and dust to pollen, microplastics, viruses, and engineered nanoparticles. These particles, some so minuscule they penetrate deep into the lungs and bloodstream, have been linked to severe health issues, including heart disease, stroke, and cancer. For over a century, the scientific community has grappled with accurately predicting the behavior of these airborne particles, particularly those with irregular shapes.
Most airborne particles defy the smooth, symmetrical shapes often assumed in traditional mathematical models. These models typically simplify particles into perfect spheres, facilitating easier equation solving but limiting the accuracy of real-world particle behavior predictions. This simplification has posed a significant challenge, especially when assessing health risks associated with irregularly shaped particles.
Reviving a Century-Old Equation for Modern Science
A researcher at the University of Warwick has made a groundbreaking advancement by introducing a straightforward method to predict the movement of particles of virtually any shape through the air. Published in the Journal of Fluid Mechanics Rapids, this study updates a formula over 100 years old, addressing a critical gap in aerosol science. Professor Duncan Lockerby, from the School of Engineering at the University of Warwick, spearheaded this research.
“The motivation was simple: if we can accurately predict how particles of any shape move, we can significantly improve models for air pollution, disease transmission, and even atmospheric chemistry. This new approach builds on a very old model — one that is simple but powerful — making it applicable to complex and irregular-shaped particles.” – Professor Duncan Lockerby
Correcting a Key Oversight in Aerosol Physics
The breakthrough emerged from revisiting one of aerosol science’s foundational tools, the Cunningham correction factor, first introduced in 1910. This factor was designed to explain how drag forces on tiny particles differ from classical fluid behavior. In the 1920s, Nobel Prize winner Robert Millikan refined the formula, but during this process, a simpler and more general correction was overlooked. Consequently, later versions of the equation remained restricted to perfectly spherical particles, limiting their applicability to real-world conditions.
Professor Lockerby’s work restructures Cunningham’s original idea into a broader and more flexible form. From this revised framework, he introduces a “correction tensor,” a mathematical tool that accounts for drag and resistance acting on particles of any shape, including spheres and thin discs. Importantly, this method does not rely on empirical fitting parameters.
“This paper is about reclaiming the original spirit of Cunningham’s 1910 work. By generalizing his correction factor, we can now make accurate predictions for particles of almost any shape — without the need for intensive simulations or empirical fitting.” – Professor Duncan Lockerby
What This Means for Pollution, Climate, and Health Research
The new model offers a robust foundation for understanding how airborne particles move across various scientific fields, including air quality monitoring, climate modeling, nanotechnology, and medicine. This approach could enhance predictions of pollution spread in urban areas, the movement of wildfire smoke or volcanic ash through the atmosphere, and the behavior of engineered nanoparticles in industrial and medical applications.
To build on this work, Warwick’s School of Engineering has invested in a new state-of-the-art aerosol generation system. This facility will enable researchers to create and study a wide variety of non-spherical particles under controlled conditions, helping to validate and refine the new predictive method.
“This new facility will allow us to explore how real-world airborne particles behave under controlled conditions, helping translate this theoretical breakthrough into practical environmental tools.” – Professor Julian Gardner, University of Warwick
The announcement comes as the scientific community continues to seek solutions to pressing environmental and health challenges. By offering a more accurate model for particle behavior, this development represents a significant leap forward in aerosol science, with potential implications for public health and environmental policy.
As researchers continue to explore the applications of this breakthrough, the potential for improved air quality models and health risk assessments becomes increasingly tangible. The move represents a pivotal moment in understanding and mitigating the impact of airborne particles on human health and the environment.
