With an annual production exceeding 390 million metric tons of plastic, the issue of plastic waste entering the environment and accumulating in rivers and other large bodies of water is escalating. Large-scale models used to estimate the transport and accumulation of said waste often neglect the effect of smaller turbulent scales.

This research focuses on studying the dynamics of floating particles in a turbulent free surface with a mean flow generated by a turbulent jet. Particles released in the surface are observed to primarily accumulate in clusters, with over 90% of all particles belonging to clusters as the seeding volume is increased. Clusters are divided into three groups based on size to highlight size-dependant clustering dynamics. The groups are defined as small, medium and large clusters. The dynamics of these clusters are studied based on the parameters size, shape and compactness, as well as the variation of those parameters over the tracked life of a cluster. A combination of these parameters is concluded to be crucial to fully characterize the cluster dynamics. Medium clusters are observed to experience the largest variations in both size and shape. The influence of the flow on the clusters is studied to conclude that turbulent flow regions lead to higher variations in both size and shape. Large-scale rotating flows are observed to vary the shape but not the size of the cluster. No flow dynamics are observed to affect the compactness.