Table of Contents
Laminar flow
When the velocity of the flow of a liquid is less than its critical velocity, the liquid flows steadily. Each layer of the liquid slides over the other layer. It behaves as if different lamina are sliding over one another. Such a flow is called laminar flow.
The surface obtained by joining the heads of the velocity vectors for the particles in a section of a flowing liquid is called a velocity profile.
(i) Velocity profile for a non-viscous liquid:
In case of a non-viscous liquid, the velocity of all the particles at any section of a pipe is same, so the velocity profile is plane as shown in Fig.
(ii) Velocity profile of a viscous liquid:
When a viscous liquid flows through a pipe, the velocity of layer at the axis is maximum, the velocity decreases as we go towards the wall of the pipe and becomes zero for the layer in contact with the pipe. Hence the velocity profile for a viscous liquid is parabolic, as shown in Fig. 10.30(b).