The fluids flow in separate layers without mixing or disruption occurring in between the layers at a particular point. The velocity of each fluid particle flowing will remain constant with time in streamline flow.A streamline flow or laminar flow is defined as one in which there are no turbulent velocity fluctuations.

Tube of Flow is defined as several streamline flows running in the same direction without intersecting(running parallelly) and interacting in each other(without friction).

One poise is the viscosity of a fluid that requires a shearing force of 1 dyne to move a square centimetre area of either of two parallel layers of fluid 1 centimetre apart with a velocity of 1 centimetre per second relative to the other layer, the space between the layers being filled with the fluid.

The dynamic viscosity η is a measure of the viscosity of a fluid. The higher the viscosity, the thicker the fluid; the lower the viscosity, the thinner it is.