| dc.description.abstract | This study investigates the Brazil Nut Effect (BNE) in a quasi-two-dimensional vertical vibrated bed by changing different fluid, vibration frequency, and water height to different density ratios of intruders under the same dimensionless vibration intensity through experiments. Take pictures with a high-speed camera and use PTV (Particle Tracking Velocimetry) to analyze the movement of particles, the rise time and velocity of the intruder, the horizontal velocity of the granular bed, and the drag force on the intruder.
When the fluid is water, the water to the particles must be taken into account. For the smaller background particles, the water dominates the size separation process, and the water drag force will make the rise time of the intruder depend on the density ratio. When the density ratio approaches the packing fraction of the small particle, the intruder needs more time to rise. In the case of changing the water height, the lower the water height, the slower the intruder rises, because the water surface close to the granular bed, which affect the upward movement of the intruder. The higher the water height, the faster the intruder rises, increasing the water height will increase the pressure difference of the granular bed, thereby increasing the velocity of the water flowing downward, making the water drag the background particles laterally faster to fill the gap under the intruder, and eventually enhance the BNE. When the water height is low, the smaller the frequency, the more severe the disturbance imposed by the water surface fluctuation on the granular bed, and the intruder with lower mass is easily affected, the stronger the input energy, the slower the rise time of the intruder. When the water height is high, the stronger the input energy can increase the net upward displacement of the intruder, thereby enhancing the water-driven BNE and reducing the rise time of the intruder. | en_US |