Renardy's team began the simulations in 1997, obtaining the code SURFER from Stephane Zaleski at the University of Paris. SURFER includes three components. The first component tracks liquid drop interfaces. The second and most time-intensive component is the solver for the governing equations of motion. The third is an algorithm used to calculate the force caused by interfacial tension. The three components work together to supply Renardy's team with information about the forces between the liquid drops that determine drop-size distribution.

When Renardy obtained SURFER, a member of Zaleski's group, Jie Li, joined the Virginia team as a postdoctoral research associate. Li taught Renardy how to use and adjust the code to calculate drop-size distribution in liquids that have factors not addressed by the original three components. For instance, they added a model to study liquids that move only after a certain amount of force is applied. The new and improved code is called SURFER++.

SURFER++ also answers questions about the effect of surfactants, which are molecules that stay on the interface between two unmixable liquids and reduce the surface tension. When the liquids are moving, these molecules move around on the interface and surface tension varies from one place to another. This variation changes the distribution pattern of the drop types. Understanding how surfactants affect the surface tension between two liquids in a given flow will provide valuable knowledge about how to work with the surfactants to affect drop-size distribution and produce emulsions that will not separate easily.

Renardy's team is now developing a different approach to both the volume-tracking component of SURFER++ and the surface tension algorithm. Their endeavor will allow the code to handle interfaces that have high curvatures, or cusping. Cusping occurs when a drop is sheared and breaks off into a daughter drop. To calculate the drop-size distribution, the team begins with a large mother drop and watches it stretch until the first daughters pinch off. The remainder of the drop looks like a cylindrical tube with pointy ends, which then retracts due to surface tension. After retraction, the ends break off again. The second generation produces daughter drops that are much smaller than the first ones. Accurate simulations that include cusping and all other possible physics occurring will provide a more complete picture of drop size distribution.