Explain the term ‘laminar flow’. Is the velocity of molecules same in all the layers in laminar flow? Explain your answer.

Laminar flow refers to a type of fluid motion characterized by smooth, orderly movement of fluid particles along parallel layers or streamlines, without any significant mixing between adjacent layers. In laminar flow, the fluid moves in a predictable, well-organized manner, with each layer of fluid sliding past adjacent layers without disruption.

In laminar flow, the velocity of fluid molecules varies across different layers. This variation in velocity is due to the frictional forces between the layers of fluid, which result in a phenomenon known as "shear." Shear occurs when adjacent layers of fluid slide past each other at different velocities, with faster-moving layers exerting a drag force on slower-moving layers. As a result, the velocity of fluid molecules is highest in the center of the flow (near the axis) and decreases gradually towards the walls of the container or pipe.

To illustrate this concept, imagine a fluid flowing through a pipe. In laminar flow, the fluid particles closest to the center of the pipe (the axis) move faster than those near the walls of the pipe. This variation in velocity creates a velocity gradient across the cross-section of the pipe, with the highest velocity at the center and progressively lower velocities towards the walls.

Therefore, in laminar flow, the velocity of molecules is not the same in all layers. Instead, the velocity varies across different layers of the fluid, with the highest velocities occurring in the center of the flow and decreasing towards the boundaries of the flow. This velocity profile is a characteristic feature of laminar flow and distinguishes it from turbulent flow, where fluid motion is chaotic and unpredictable.