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FLUID MECHANICS

CHAPTER 4 : FLUID DYNAMICS

4.0 FLUID DYNAMICS

In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that

describes the flow of fluids—liquids and gases. It has several subdisciplines, including
aerodynamics and hydrodynamics.

4.1 DIFFERENT TYPES OF FLOW

a. Uniform flow

The cross-sectional area and velocity of the stream of fluid are the same at each

successive cross-section. Example: flow through a pipe of uniform bore running
completely full.

b. Steady flow

The cross-sectional area and velocity of the stream may vary from cross-section,

but for each cross-section they do not change with time. Example: a wave

travelling along a channel.

c. Laminar flow

Also known as streamline or viscous flow, in which the particles of the fluid move

in an orderly manner and retain the same relative positions in successive cross-
sections. (Figure 4.1)

d. Transitional Flow

On applying external disturbance, we find there are irregular fluctuations.

Intermittent laminar and turbulent flow occur, i.e. phases occur in the flow in

which the flow is laminar and phases in which the flow shows turbulent

characteristics. (Figure 4.1)

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