The lower the viscosity, the more turbulent and extended the flow. This flow is usually described in terms of intensity by measuring the fluctuating velocity relative to the mean velocity. In rare cases where the root-mean-square fluctuating velocities are equal, a condition known as isotropic turbulence exists. But this type of turbulence is generally irrotational (i.e., lacking in rotation or vorticity).
Turbulence can be further described in terms of a Reynolds number, a dimensionless value computed from the flow velocity, density and viscosity of the fluid. Reynolds numbers have been used for many years to delineate the boundary between turbulent flow and stable laminar flow.