Professor Excels in "Electrospray" Droplet Research

After 30 years in the field, Osman Basaran knows all about the effects of electric fields on fluids. The Chemical Engineering Reilly Professor of Fluid Mechanics recently co-advised with Professor Michael Harris on a project to mathematically describe exactly how droplets form when liquids are exposed to electric fields.

The breakthrough could result in a variety of applications, from a type of industrial painting called electrospraying, to analyzing molecules in analytical chemistry, to manufacturing tiny micro- and nanoparticles for research and industry.

“Our approach allowed us to do this multi-scale modeling in one big calculation,” says Basaran. An electric field causes liquid drops to form structures that have a perfect cone at the leading edge. Using a precise method called finite elements with elliptic mesh generation, researchers can break down a material into many smaller segments and separately solve the mathematical equations governing their behaviors.

“We studied higher viscosity fluids to see their effects,” Basaran says. Viscosity plays a vital role in drop formation and size, contradicting conventional wisdom and past research, which concentrated on lower viscosity fluids like water. Basaran and other Purdue researchers conducted experiments with liquids that were similar to fuels.“ This may prove to be important in combustion applications because fuel is sprayed into engine cylinders using fuel injectors,” he says.

The findings are detailed in a paper appearing in the January 2008 issue of Nature Physics. The paper was written by ChE senior Jeremy Jones, doctoral student Robert Collins, and ChE Professors Michael Harris and Basaran.

- Rebecca Goldenberg and Emil Venere