This course provides students with an introduction to principal concepts and methods of fluid mechanics. Topics covered include volume and mass flow, Bernoulli's equation, viscosity, flow losses in pipes, dimensional analysis of fluid flow, and the development of similarity relationships. Students will study and analyze fluid systems, develop problem-solving skills, and demonstrate their understanding through assignments and exams.

1. FLUID MECHANICS

2. COURSE DESCRIPTION
 This course provides students with an introduction to principal concepts and
methods of fluid mechanics.
 Topics covered in the course include volume and mass flow, Venturi meter,
Bernoulli's equation, Jets, Orifice coefficients, Dynamic and kinematic viscosity,
Reynolds' number, Flow losses in pipes and fittings, Darcy's formula, Centrifugal
pumps, Flow through pipes, Dimensional analysis of fluid flow including the
development of similarity relationships.
 Using these concepts, the students will study, analyze, and design fluid systems,
as well as develop the problem-solving skills essential to good engineering
practice of fluid mechanics in practical applications.
 Students will also have the opportunity to demonstrate a familiarity and ability
to work on fluid mechanics.
 These outcomes will be demonstrated through an assessment of assignments
and examinations.

3. WHAT IS FLUID MECHANICS?
 A branch of science that deals with the behavior of the
fluids (liquids or gases) at rest and in motion.
 It deals with the static, kinematics and dynamic aspects of
fluids.
 Fluid statics: the study of fluids at rest.
 Fluid kinematics: the study of fluids in motion (where
pressure forces are not considered).
 Fluid dynamics: the study of fluids in motion (where
pressure forces are considered).

4. DISTICTION BETWEEN LIQUID AND GAS
 LIQUID
1. It has a free surface.
2. A given quantity of liquid occupies a given volume of a container.
3. It is incompressible.
 GAS
1. It has no free surface 2.
2. A given quantity of gas occupies all portions of the container regardless of its
shape and size. 3.
3. It is compressible
 Free Surface - a surface in which all pressures can be removed except its own
vapor pressure.
 Vapor - is a gas in which its pressure and temperature are such that very near to
its liquid state.

5. PROPERTIES OF FLUIDS
 Density (Mass Density): It is defined as the ratio of the mass of a
fluid to its volume.
 The density of liquids may be considered as constant while that
of gases changes with the variation of pressure and temperature.
 The unit of mass density in SI unit is kg per cubic meter (i.e.,
kg/m3).
 Density is denoted by the symbol ƍ (rho).
 Mathematically, mass density is written as
ƍ =
𝑀𝑎𝑠𝑠 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑
𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑
 The value of density of water is 1gm/cm3 or 1000 kg/m3.
Z Emmanuel Gweh III

6. PROPERTIES OF FLUIDS (Continued)
 Specific Weight or Weight Density: the ratio between the weight of a fluid
to its volume.
 It is denoted by the symbol w.
 Mathematically,
𝑤 =
𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑
𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑
=
𝑀𝑎𝑠𝑠 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑 ∗ 𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 𝑑𝑢𝑒 𝑡𝑜 𝑔𝑟𝑎𝑣𝑖𝑡𝑦
𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑
=
𝑀𝑎𝑠𝑠 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑 ∗ 𝑔
𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑
= ƍ ∗ g
𝑤 = ƍ ∗ g
 The value of specific weight (specific density) for water is 9.81* 1000 N/m3
in SI unit.

7. PROPERTIES OF FLUIDS (Continued)
 Specific Volume: the volume of a fluid occupied by a unit mass.
 It is the reciprocal of mass density.
 It is expressed as m3/kg.
 It is commonly applied to gases.
 Mathematically, it is expressed as
𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑
𝑀𝑎𝑠𝑠 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑
=
1
𝑀𝑎𝑠𝑠 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑
𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑓𝑙𝑢𝑖𝑑
=
1
ƍ

8. PROPERTIES OF FLUIDS (Continued)
 Specific Gravity: the ratio of the weight density (density) of a fluid to the weight
density (density) of a standard fluid.
 For liquids, the standard fluid is taken as water.
 And for gases, the standard fluid is taken as air.
 Specific Gravity is called relative density.
 It is a dimensionless quantity and is denoted by the symbol S.
 Mathematically,
𝑆(𝑓𝑜𝑟 𝑙𝑖𝑞𝑢𝑖𝑑𝑠) =
𝑊𝑒𝑖𝑔ℎ𝑡 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑙𝑖𝑞𝑢𝑖𝑑
𝑊𝑒𝑖𝑔ℎ𝑡 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟
𝑆(𝑓𝑜𝑟 𝑔𝑎𝑠𝑒𝑠) =
𝑊𝑒𝑖𝑔ℎ𝑡 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑔𝑎𝑠
𝑊𝑒𝑖𝑔ℎ𝑡 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑎𝑖𝑟
𝑇ℎ𝑢𝑠 𝑤𝑒𝑖𝑔ℎ𝑡 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑎 𝑙𝑖𝑞𝑢𝑖𝑑 = 𝑆 ∗ 𝑊𝑒𝑖𝑔ℎ𝑡 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟
= 𝑆 ∗ 1000 ∗ 9.81
𝑁
m3
𝑇ℎ𝑒 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑎 𝑙𝑖𝑞𝑢𝑖𝑑 = 𝑆 ∗ 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟
= 𝑆 ∗ 1000
𝑘𝑔
m3
Z Emmanuel Gweh III

9. PROPERTIES OF FLUIDS (Continued)
 If the specific gravity of a fluid is known, then the
density of the fluid will be equal to the specific gravity
of fluid multiplied by the density of water.
 For example, the specific gravity of mercury is 13.6,
hence the density of mercury = 13.6 * 1000 =13600
kg/ m3.
Z Emmanuel Gweh III

10. SAMPLE PROBLEMS
1. Calculate the specific weight, density
and specific gravity of one liter of a
liquid which weighs 7 N.
2. Calculate the density, specific weight
and weight of one liter of petro of
specific gravity = 0.7.

11. PROPERTIES OF FLUIDS (Continued)
 Viscosity: the property of a fluid which offers resistance to the movement of one
layer of fluid over another adjacent layer of the fluid.
 When two layers of a fluid, a distance ‘dy’ apart, move one over the other at
different velocities (say u + du), the viscosity together with relative velocity causes
a shear stress acting between the fluid layers.
 The top layer causes a shear stress on the adjacent layer while the lower layer
causes a shear stress on the adjacent top layer.
 This shear stress is proportional to the rate of change of velocity with respect to y.
 It is denoted by the symbol Ʈ (Tau).
 Mathematically,Ʈ⍺
𝑑𝑢
𝑑𝑦
Ʈ = µ
𝑑𝑢
𝑑𝑦