Hjulström diagram

A diagram showing the relationship in a channel between particle size and the mean fluid velocity required for entrainment.It shows that an entrained particle can be transported in suspension at a lower velocity than that required to lift the particle initially. When the stream velocity slows to a critical speed, the particle is deposited.

Note that higher velocities are needed for the entrainment of clay-sized particles because of the electrostatic forces which bind them together.

Hjulström diagram