Titan has a thick, hazy nitrogen and methane atmosphere, rivers and lakes of liquid methane and ethane, and equatorial dunes. The dune 'sand' likely forms from atmospheric haze particles, about 1 micrometer in size. However, models of wind driven movement of particles, saltation, show that sand on Titan has an ideal size of 100–600 micrometers, suggesting that these small particles must grow in size after settling on the surface.

This study tested whether flocculation, a process where particles in liquid collide and stick together, could create larger, sand-sized clumps in Titan's rivers. We mixed Titan haze analogs, 'tholins, in hexane, a liquid with similar properties to Titan’s rivers, under different conditions, including strong turbulent mixing.

Previous work shows that without turbulence, particle clumps stayed small, around 10–20 micrometers. Our results show that with turbulent mixing, clumps as large as 300 micrometers formed, while still being made of the 1 micrometer particles. This shows that turbulent liquid on Titan could help produce sand-sized particles from the atmospheric haze. These larger clumps could then be moved by wind to form the dunes seen on Titan’s surface. Future work will test how resistant these clumps are to erosion and deformation.