Fluidization (or fluidisation)'s a process similar to liquefaction whereby a granular material's converted from a static solid-like state to a dynamic fluid-like state. This process occurs when a fluid (liquid or gas)'s passed up through the granular material. When a gas flow's introduced through the bottom of a bed of solid particles, it'll move upwards through the bed via the empty spaces between the particles. At low gas velocities, aerodynamic drag on each particle's also low, and thus the… (More on Fluidization)