SELF-ORGANIZATION AND CHAOS IN A FLUIDIZED-BED

We present experimental evidence that a complex system of particles su spended by upward-moving gas can exhibit low-dimensional bulk behavior . Specifically, we describe large-scale collective particle motion ref erred to as slugging in an industrial device known as a fluidized bed. As gas flow increases from zero, the bulk motion evolves from a fixed point to periodic oscillations to oscillations intermittently punctua ted by ''stutters,'' which become more frequent as the flow increases further. At the highest flow tested, the behavior becomes extremely co mplex (''turbulent'').