This document defines key concepts related to fluids, including definitions of fluid, density, viscosity, temperature, pressure, and other fluid properties. It explains that fluids include both liquids and gases, and that they continuously deform under shear stress. It also discusses fluid flow regimes including laminar and turbulent flow. Additional concepts covered include buoyancy, drag, and lift forces. Buoyancy is defined as a vertical force that can be positive, negative, or neutral. The three types of drag - frictional, form, and wave drag - are explained. Finally, it notes that lift is a force perpendicular to fluid flow, and that factors like density, viscosity, and flow speed affect lift.

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3. THE NATURE OF FLUIDS
FLUID
 Fluid is any substance that tend to flow or
continuously deform when acted on by a shear force.
 Substance that flows when subjected to shear stress.
 Both gases and liquids are fluids with similar
mechanical behaviors.
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4. THE NATURE OF FLUIDS
 The ability to control the action of fluid forces
differentiate elite from average swimmers.
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5. THE NATURE OF FLUIDS
Relative motion
 The velocity of a body relative to a fluid influences
the magnitude of the forces exerted by the fluid on
the body.
 Because a fluid is a medium capable of flow the
influence of the fluid on a body moving through it
depends not only on the body velocity but also on the
velocity of fluid.
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6. THE NATURE OF FLUIDS
 PROPERTIES OF FLUIDS
 Density
 Viscosity
 Temperature
 Pressure
 Specific Volume
 Specific Weight
 Specific Gravity
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7. THE NATURE OF FLUIDS
Density
 Density is the mass per unit volume of a fluid.
Viscosity
 Viscosity is the fluid property that determines the
amount of resistance of the fluid to shear stress.
Temperature
 It is the property that determines the degree of
hotness or coldness or the level of heat intensity of a
fluid.
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8. THE NATURE OF FLUIDS
Pressure
 Pressure of a fluid is the force per unit area of the fluid.
Specific Volume
 Specific volume is the volume of a fluid (V) occupied per
unit mass (m). It is the reciprocal of density.
Specific Weight
 Specific weight is the weight possessed by unit volume of
a fluid
Specific Gravity
 Specific gravity is the ratio of specific weight of the given
fluid to the specific weight of standard fluid
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9. THE NATURE OF FLUIDS
 LAMINAR FLOW
 laminar flow is characterized by a smooth parallel
layers of fluid.
 TURBULENT FLOW
 Turbulent flow is characterized by a mixing adjacent
layers of fluid.
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10. BUOYANCY
BUOYANCY
 is a force on an object making that object rise or
move upward.
 Buoyancy is a fluid force that always acts vertically
upward.
 Three Types of Buoyancy
 Positive Buoyancy
 Negative Buoyancy
 Neutral Buoyancy
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11. BUOYANCY
o POSITIVE BUOYANCY
 Positive buoyancy occurs when an object is lighter
than the fluid it displaces.
o Negative Buoyancy
 Negative buoyancy occurs when an object is denser
than the fluid it displaces.
o Neutral Buoyancy
 Neutral buoyancy occurs when an object’s weight is
equal to the fluid it displaces.
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12. BUOYANCY
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13. BUOYANCY
o WHAT DETERMINES WHETHER A BODY FLOATS
OR SINKS
 Floating occur when the buoyant force is greater
then or equal to the body weight.
 Sinking occur when the body weight is greater then
buoyant force.
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14. DRAG
 Drag is a force caused by the dynamic action of a
fluid that acts in the direction of the free stream fluid
flow.
 Generally resistance force caused by the motion of a
body through a fluid, such as water or air.
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15. DRAG
Drag Force
 A drag force is the resistance force caused by the
motion of a body through a fluid, such as water or
air.
 A drag force acts opposite to the direction of the
oncoming flow velocity. This is the relative velocity
between the body and the fluid.
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16. DRAG
FRICTIONAL DRAG
 Also known as Skin Friction Drag, is drag caused by
the friction of a fluid against the surface of an object
that is moving through it.
 It is directly proportional to the area of the surface
in contact with the fluid and increases with the
square of the velocity.
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17. DRAG
FORM DRAG
 Form drag: resistance caused by an object’s shape
and profile as it moves through a fluid.
 A form drags depends on your body types.
 If your body is larger than the persons next to you,
you will have to overcome more drags than the
persons next to you.
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18. DRAG
 WAVE DRAG
 Wave drag: Resistance caused by turbulence in a
fluid.
 Wave drag is form when a swimmers is moving in
the water.
 The faster you swim the more wave drag you created.
For example if one person is jumping up and down
in the water quickly and sloppily, you could see a big
wave around the person.
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19. LIFT FORCE
 A force acting on a body in a fluid in a direction
perpendicular to the fluid flow.
 Generally a resistance force that tend to slow the
motion of a body moving through a fluid.
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20. LIFT FORCE
WHAT FACTORS THAT AFFECT LIFT FORCE
 Density
 viscosity
 speed of flow
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21. LIFT FORCE
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22. LIFT FORCE
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