Dispersion Coefficient at Dispersion Number < 0.01 is distinguished as Spreading of the Tracer in the reactor, that diffuses across a unit area in 1 s under the influence of a gradient of one unit. And is denoted by Dp. Dispersion Coefficient at Dispersion Number < 0.01 is usually measured using the Square Meter Per Second for Diffusivity. Note that the value of Dispersion Coefficient at Dispersion Number < 0.01 is always positive.