• The course will introduce fluid mechanics and establish its relevance in civil engineering.
• Develop the fundamental principles underlying the subject.
• Demonstrate how these are used for the design of simple hydraulic components.

• Lectures:
  20 Classes presenting the concepts, theory and application.
  Worked examples will also be given to demonstrate how the theory is applied. You will be asked to do some calculations - so bring a calculator.
• Assessment:
  
  • 1 Exam of 2 hours (80 %)
    This consists of 6 questions of which you choose 4.
  • 2 Multiple choice question papers. (2x5% = 10 %)
    These will be set throughout the module during the lectures
  • 1 Marked problem sheet. (10%).
• Laboratories: 2 x 3 hours
  These two laboratory sessions examine how well the theoretical analysis of fluid dynamics describes what we observe in practice.
  During the laboratory you will take measurements and draw various graphs according to the details on the laboratory sheets. These graphs can be compared with those obtained from theoretical analysis.
  You will be expected to draw conclusions as to the validity of the theory based on the results you have obtained and the experimental procedure.
  After you have completed the two laboratories you should have obtained a greater understanding as to how the theory relates to practice, what parameters are important in analysis of fluid and where theoretical predictions and experimental measurements may differ.
  The two laboratories sessions are:
  1. Impact of jets on various shaped surfaces - a jet of water is fired at a target and is deflected in various directions. This is an example of the application of the momentum equation.
  2. The rectangular weir - the weir is used as a flow measuring device. Its accuracy is investigated. This is an example of how the Bernoulli (energy) equation is applied to analyses fluid flow.
  [As you know, these laboratory sessions are compulsory course-work. You must attend them. Should you fail to attend either one you will be asked to complete some extra work. This will involved a detailed report and further questions. The simplest strategy is to do the lab.]
• Homework:
  Example sheets: These will be given for each section of the course. Doing these will greatly improve your exam mark. They are course work but do not have credits toward the module.
  Lecture notes: Theses should be studied but explain only the basic outline of the necessary concepts and ideas.
  Books: It is very important do some extra reading in this subject. To do the examples you will definitely need a text book. Any one of those identified below is adequate and will also be useful for the fluids courses in higher years.
  • Example classes:
    There will be example classes each week. You may bring any problems/questions you have about the course and example sheets to these classes.

• Introduction

• Fluid Properties
  • Fluids vs. Solids
  • Viscosity
  • Newtonian Fluids
  • Properties of Fluids
• Statics
  • Hydrostatic pressure
  • Manometry / pressure measurement
  • Hydrostatic forces on submerged surfaces
• Dynamics
  • The continuity equation.
  • The Bernoulli Equation.
  • Applications of the Bernoulli equation.
  • The momentum equation.
  • Application of the momentum equation.
• Real Fluids
  • Boundary layer.
  • Laminar flow in pipes.
• Introduction to dimensional analysis
  • Dimensional analysis
  • Similarity

Any of the book listed below are more than adequate for this module.

(You will probably not need any more fluid mechanics books on the rest of the Civil Engineering course)

Mechanics of Fluids, Massey B S., Van Nostrand Reinhold.

Fluid Mechanics, Douglas J F, Gasiorek J M, and Swaffield J A, Longman.

Civil Engineering Hydraulics, Featherstone R E and Nalluri C, Blackwell Science.

Hydraulics in Civil and Environmental Engineering, Chadwick A, and Morfett J., E & FN Spon - Chapman & Hall.

The lecture notes you are reading can be found on the WWW at he following address:

These notes give more information than is found in the lectures although they must also be read along with other fluid mechanics books. They may be read on line or printed off for personal use.

Why are we studying fluid mechanics on a Civil Engineering course? The provision of adequate water services such as the supply of potable water, drainage, sewerage are essential for the development of industrial society. It is these services which civil engineers provide.

Fluid mechanics is involved in nearly all areas of Civil Engineering either directly or indirectly. Some examples of direct involvement are those where we are concerned with manipulating the fluid:

• Sea and river (flood) defences;
• Water distribution / sewerage (sanitation) networks;
• Hydraulic design of water/sewage treatment works;
• Dams;
• Irrigation;
• Pumps and Turbines;
• Water retaining structures.

And some examples where the primary object is construction - yet analysis of the fluid mechanics is essential:

• Flow of air in / around buildings;
• Bridge piers in rivers;
• Ground-water flow.

Notice how nearly all of these involve water. The following course, although introducing general fluid flow ideas and principles, will demonstrate many of these principles through examples where the fluid is water.

As any quantity can be expressed in whatever way you like it is sometimes easy to become confused as to what exactly or how much is being referred to. This is particularly true in the field of fluid mechanics. Over the years many different ways have been used to express the various quantities involved. Even today different countries use different terminology as well as different units for the same thing - they even use the same name for different things e.g. an American pint is 4/5 of a British pint!

To avoid any confusion on this course we will always used the SI (metric) system - which you will already be familiar with. It is essential that all quantities be expressed in the same system or the wrong solution will results.

Despite this warning you will still find that that this is the most common mistake when you attempt example questions.

The SI system consists of six primary units, from which all quantities may be described. For convenience secondary units are used in general practise which are made from combinations of these primary units.

Primary Units

The six primary units of the SI system are shown in the table below:

Quantity	SI Unit	Dimension
length	metre, m	L
mass	kilogram, kg	M
time	second, s	T
temperature	Kelvin, K	Q
current	ampere, A	I
luminosity	candela	Cd

In fluid mechanics we are generally only interested in the top four units from this table.

Notice how the term 'Dimension' of a unit has been introduced in this table. This is not a property of the individual units, rather it tells what the unit represents. For example a metre is a length which has a dimension L but also, an inch, a mile or a kilometre are all lengths so have dimension of L.

(The above notation uses the MLT system of dimensions, there are other ways of writing dimensions - we will see more about this in the section of the course on dimensional analysis.)

Derived Units

There are many derived units all obtained from combination of the above primary units. Those most used are shown in the table below:

Quantity	SI Unit		Dimension
velocity	m/s	ms-1	LT-1
acceleration	m/s2	ms-2	LT-2
force	N kg m/s2	kg ms-2	M LT-2
energy (or work)	Joule J N m, kg m2/s2	kg m2s-2	ML2T-2
power	Watt W N m/s kg m2/s3	Nms-1 kg m2s-3	ML2T-3
pressure ( or stress)	Pascal P, N/m2, kg/m/s2	Nm-2 kg m-1s-2	ML-1T-2
density	kg/m3	kg m-3	ML-3
specific weight	N/m3 kg/m2/s2	kg m-2s-2	ML-2T-2
relative density	a ratio no units		1 no dimension
viscosity	N s/m2 kg/m s	N sm-2 kg m-1s-1	M L-1T-1
surface tension	N/m kg /s2	Nm-1 kg s-2	MT-2

The above units should be used at all times. Values in other units should NOT be used without first converting them into the appropriate SI unit. If you do not know what a particular unit means find out, else your guess will probably be wrong.
One very useful tip is to write down the units of any equation you are using. If at the end the units do not match you know you have made a mistake. For example is you have at the end of a calculation,

you have certainly made a mistake - checking the units can often help find the mistake.

More on this subject will be seen later in the section on dimensional analysis and similarity.