Question

How does turbulent flow differ from laminar flow? For which flow is the heat transfer coefficient higher?

Answer 1

LAMINAR FLOW

The fluid flow in which the adjacent layers of the fluid do not mix with each other and moves parallel to each other, is called laminar flow.

In the laminar flow, the fluid layer moves in straight line.

The laminar flow always occurs when the fluid flow with low velocity and in small diameter pipes.

The fluid flow having Reynolds number less than 2000 is called laminar flow.

The fluid flow is very orderly i.e. there is no mixing of adjacent layers of the fluid and they move parallel to each other and also with the walls of the pipe.

Shear stress in laminar flow depends only on the viscosity of the fluid and independent of the density.

TURBULENT FLOW
The fluid flow in which the adjacent layers of the fluid cross each other and do not move parallel to each other, is called turbulent flow.

In turbulent flow the fluid layers do not moves in straight line. They move randomly in zigzag manner.

The turbulent flow occurs when the velocity of the fluid is high and it flows through larger diameter pipes.

The fluid flow having Reynolds number greater than 4000 is called turbulent flow.

The fluid does not flow in definite order. There is a mixing of different layers and they do not move parallel to each other but crosses each other.

The shear stress in turbulent flow depends upon its density.