Archimedes number

The Archimedes number is a dimensionless ratio of buoyancy forces to viscous forces in fluid flow. It helps characterize particle settling, rising, and fluidization.

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Galileo number: A dimensionless number comparing gravitational forces with viscous forces in fluid flow. It shares the Archimedes number’s force-balance structure and connects particle motion to gravity.
Fluidization: The suspension of solid particles by an upward-flowing fluid, giving the bed fluid-like behavior. The Archimedes number helps classify fluidization regimes and particle-fluid operating conditions.
Buoyancy: The upward force exerted by a fluid on an immersed body, equal to the weight of displaced fluid. Buoyancy contributes to the net driving force behind particle settling and rising.
Reynolds number: A dimensionless ratio of inertial forces to viscous forces in fluid flow. Unlike the Archimedes number, it characterizes an existing flow rather than particle and fluid properties driving it.
Particle settling: The downward movement of suspended particles through a fluid under gravity. The number helps characterize when settling is dominated by viscosity or inertia.
Minimum fluidization velocity: The lowest fluid velocity at which a packed particle bed becomes suspended and fluidized. It is estimated from particle and fluid properties summarized by dimensionless groups including the Archimedes number.
Viscosity: A measure of a fluid’s resistance to deformation and flow. Viscosity sets the strength of the resisting force in the Archimedes number’s comparison.
Froude number: A dimensionless ratio comparing inertial effects with gravitational effects in flow. It balances inertia against gravity, whereas the Archimedes number balances buoyancy-related forces against viscosity.
Stokes' law: A relation giving the drag force on a small sphere moving slowly through a viscous fluid. At low particle Reynolds number, it provides a settling regime that the Archimedes number helps identify.
Wen–Yu correlation: An empirical correlation relating minimum fluidization conditions to particle and fluid properties. It uses the Archimedes number to estimate the Reynolds number at incipient fluidization.