1. Chapter 3 Fluid Statics

2. Main Topics Introduction Pressure Variation in a Static Fluid
Equilibrium of a fluid of constant density
The measurement of Pressure
The Barometer
Manometers
The Bourdon Gauge
Other types of Pressure Gauge
Uniform Rectilinear Acceleration
Pressure Variation in a variable density fluid and the Standard Atmosphere

3. 3.0 Introduction
Fluid Statics is a branch of mechanics of fluid which deals primarily with fluids at rest. As individual elements do not move relative to each other, shear stresses are not involved and all forces due to the pressure of the fluid are normal to the surfaces on which they acts.

4. 3.1 Pressure variation in a static fluid
Fig.3.1.1
Derivation of (eq.3.1.1)
Equation (3.1.1) is the basic equation of fluid statics and it states that the maximum rate of change of pressure occurs in the direction of the gravitational vector.

5. 3.2 Equilibrium of a fluid of constant density
Assumptions:
Constant density
Gravitational acceleration in negative z direction
Deriving eq.3.2.1
Assumptions:
Constant density (liquid)
Gravitational acceleration in negative z direction
Relating to liquid surface
Deriving eq.3.2.2

6. 3.3 The Measurement of Pressure
The Barometer
Fig
The governing equation is
Manometers
Fig

7. 3.3 The Measurement of Pressure
Applying manometer on a pipe
Fig
The governing equation is
The Bourdon Gauge
Fig
Other types of Pressure Gauge
e.g., strain-gage pressure transducer

8. 3.4 Uniform Rectilinear Acceleration
Fig.3.1.1*
Derivation of eq.3.4.1
Example 3.4.1

9. 3.5 Pressure Variation in a variable-density fluid and the Standard Atmosphere
For ideal gas under isothermal condition
derivation of (eq.3.5.3)
For ideal gas under adiabatic condition
governing equations (3.5.4) & (3.5.5)
U.S. Standard Atmosphere (Fig.3.5.1)
in Troposphere – (eq.3.5.7)
in Stratosphere – (eq.3.5.8)

10. Points to remember The governing equation for static fluid is
The above equation applies to static fluid where there is no relative motion between fluid particles.
For static fluid, the maximum rate of change of pressure is along the gravitational acceleration and the constant pressure line is perpendicular to the gravitational acceleration.
Constant pressure line is for fluid with continuous phase.

11. Tutorial
Link to Tutorial 2