Drag force in random arrays of mono- and bidisperse spheres

Fluid-particle contact is essential in many processes in the chemical, petrochemical, metallurgical and food processing industry. A reactor type which is particularly successful in establishing a thorough contact between fluid and particles, and has excellent heat and mass transfer properties, is the fluidised bed reactor. In these reactors the interaction between fluid and particles (drag force) balances the gravity acting on the particles, with the effect that the particles `float¿ in the reactor, which enhances mixing properties.