Give examples where such a flow is encountered.

(5 Marks) Dec-2018.

Subject Fluid Mechanics 2

Topic Laminar Flow

Difficulty Medium

Characteristic Of Laminar Flow

• Laminar is characterized by smooth streamlines and highly ordered motion. Under most practical conditions, the flow in a circular pipe is laminar for Re < 2000. In fully de$eloped laminar flow, each fluid particle moves at a constant axial velocity along a streamline and the velocity profile remains unchanged in the flow direction.

• The steady laminar flow of an incompressible fluid with constant properties in the fully developed region of a straight circular pipe.

• Laminar flow in a straight pipe may be considered as the relative motion of a set of concentric cylinders of fluid, the outside one fixed at the pipe wall and the others moving at increasing speeds as the center of the pipe is approached.

• Smoke rising in a straight path from a cigarette is undergoing laminar flow. After rising a small distance, the smoke usually changes to turbulent flow, as it eddies and swirls from its regular path.

Examples

• Laminar flow is common only in cases in which the flow channel is relatively small, the fluid is moving slowly, and its viscosity is relatively high.
• Oil flow through a thin tube or blood flow through capillaries is laminar. Most other Kinds of fluid flow are turbulent except near solid boundaries, where the flow is often laminar, especially in a thin layer just adjacent to the surface