Drag and lift modulation of a towed intruder in granular media via vibration and passive compliance

Understanding how intruders interact with granular media is critical for both fundamental physics and engineering applications. In this work, we investigate how different disturbance strategies —internal vibration and lateral wheels— modulate drag and lift forces on a body towed through a granular bed. A modular test platform was developed to compare six configurations under identical conditions: a smooth baseline, vibration, locked wheels, active wheels, passive wheels, and a vibration-assisted passive condition. Direct force measurements reveal that vibration significantly reduces drag and decreases the magnitude of reverse lift by fluidizing grains and weakening force chains. In contrast, wheel-based strategies operate through surface interaction: locked wheels amplify both drag and reverse lift, active wheels provide only partial relief relative to the locked case and still exceed baseline forces, while the passive wheels achieve modest drag reduction and exert only a minimal influence on reverse lift through their adaptive alignment with the grain flow. These results demonstrate two distinct pathways for resistance reduction: energetic fluidization and passive compliance. Beyond their engineering relevance, the findings provide new physical insights into how granular compaction, force-chain stability, and structural adaptation govern drag and lift forces in particulate media.