Pebbles settle faster in water than do grains of sand, and any particle settles more slowly in a viscous fluid such as oil. An understanding of grain settling is important in analyzes sediment transport and deposition. The turbulent eddies of flowing water in a river or ocean current lift sediment particles above the bottom and transport them in suspension. This process depends on the settling velocities of the grains, the lower their settling rate the higher the grains are lifted above the bottom and the greater their concentration. As the strength of the current wanes, the grains are deposited on the bed at rates that depend on their settling velocities.
A number of studies have been conducted to measure settling velocities of sediment grains, with the analyzes relating the settling to the sizes and densities of the grains. Such measurements are usually made in a cylindrical tube filled with water. When the grain is released in the water, it initially accelerates, increasing