Ch 1 Introduction

1-1  Note to Students
1-2  Definition of a Fluid
1-3  Scope of Fluid Mechanics
1-4  Basic Equations
1-5  Methods of Analysis
        System and Control Volume
        Differential versus Integral Approach
1-6  Dimensions and Units
        Systems of Dimensions
        Systems of Units
        Preferred Systems of Units
1-7  Summary
        Problems

1-1 Note to Students

We can get inspiration by observing the creature.

1-2 Definition of A Fluid

A fluid is a substance that deforms continuously under the application of a shear (tangential)
stress no matter how small the shear stress may be.

 

Behavior of a solid and a fluid, under the action of a constant shear force.

The fluids comprise the liquid and gas (or vapor) phases of the physical forms in which matter

exists. A solid solid deforms when a shear stress is applied, but its deformation does not

continue to increase with time. 

When the shear force is applied to the upper plate, the deformation of the fluid element 

continues to increase as long as the force is applied. 

1-3 Scope of Fluid Mechanics

 Everywhere and anytime, you can find fluid mechanics.

1-4 Basic Equations 

1. The conservation of mass.

2. Newton's second law of motion.

3. The principle of angular momentum.

4. The first law of thermodynamics.

5. The second law of thermodynamics.

Many problems it is necessary to bring into the analysis additional relations that describe the

behavior of physical properties of fluids under given conditions.

We must emphasize that there are, as we shall see, many apparently simple problems in fluid

mechanics that cannot be solved analytically. In such cases we must resort to more complicated

numerical solutions and/or results of experimental tests.

1-5 Methods of Analysis 

The first in solving a problem is to define the system that you are attempting to analyze. 

In basic mechanics, we made extensive use of the free-body diagram. We will use a system or

control volume, depending on the problem being studies.