Experimental and Mechanistic Study on Immersion Behavior of Heterogeneous Particle Beds

This study experimentally investigates the immersion behavior of steel and titanium cylinders in spherical and cylindrical heterogeneous particle beds saturated by a Newtonian liquid. The effects of cylinder density, different particle-bed systems, liquid viscosity, bed solid volume fraction, and intruding cylinder aspect ratio on immersion depth are systematically analyzed. Particle trajectories in liquid-saturated beds are recorded using a digital camera at 100 frames per second (fps) and are analyzed by image-processing techniques. Related particle-resolved simulation studies are conducted to support the mechanistic interpretation. Results show that particles with higher density tend to achieve greater immersion depths due to their larger gravitational driving force. Compared with spherical beds, cylindrical beds exhibit different immersion responses depending on liquid viscosity and experimental conditions. In the selected viscosity-comparison cases, the spherical bed gives a larger immersion depth than the cylindrical bed under the lower-viscosity condition, whereas the cylindrical bed gives a larger immersion depth under the higher-viscosity condition. Compacting the bed increases its solid volume fraction, thereby increasing resistance and reducing immersion depth.