Drag Forces on Plastic Bag Marine Debris

Plastic debris, including thin-film plastic bags, pose physical, chemical, and biological threats to marine life. Effective marine plastic removal strategies require an understanding of long-range debris trajectories, which are driven by hydrodynamic drag characteristics. For this study, drag forces were measured by towing a standard, plastic grocery bag through a water tank at varied speeds. Drag force profiles of the plastic bag sample for constant and sinusoidal speed tests in the tow tank demonstrated a parabolic relationship between speed and drag force that accurately predicted horizontal drag in sinusoidal motion. Results can inform MIT Sea Grant's design of a spatially tracked marine surface drifter mimicking hydrodynamic behavior of plastic bags, providing an empirical basis for predicting plastic bag accumulation zones and facilitating strategic removal.