Experiment on Fluidization in Unbounded Domains

One‐dimensional fluidization in a bounded domain is a well‐understood phenomenon. However, in unbounded domains, the formation of an interface between the fluidized and unfluidized regions is a complicated phenomenon that is poorly understood at present. This experimental study advances the fundamental understanding of two‐dimensional fluidization and provides a data base for future numerical modeling. The study was performed in a $365.7\mathrm{cm}\times 121.9\mathrm{cm}\times 30.4\mathrm{cm}(12\mathrm{ft}\times 4\mathrm{ft}\times 1\mathrm{ft})$ tank filled with sand overlying a small source pipe. The back panel contains 143 pressure taps used to determine the hydraulic head distribution. For the bed depths tested, the lines of constant hydraulic head are horizontal in the fluidized region and curve downward in the unfluidized region. The one‐dimensional theoretical superficial velocity needed to initiate fluidization provides a reasonable approximation of the two‐dimensional incipient fluidization conditions. The average sand concentration in the fluidized region decreases with increased flow rate. The total leakage occurring across the interface from the fluidized region to the unfluidized region was determined to be less than 5% of the total fluidization flow rate entering the system.