Fluid Mechanics - PowerPoint PPT Presentation

Loading...

PPT – Fluid Mechanics PowerPoint presentation | free to download - id: 70fb65-MzI2M



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Fluid Mechanics

Description:

Fluid Mechanics Liquids and gases ... (PV is energy, more later) When the speed of a fluid ... Times Default Design Microsoft Equation 3.0 Fluid Mechanics Density ... – PowerPoint PPT presentation

Number of Views:25
Avg rating:3.0/5.0
Slides: 28
Provided by: Robert2068
Learn more at: http://simeonca.org
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Fluid Mechanics


1
Fluid Mechanics
  • Liquids and gases have the ability to flow
  • They are called fluids
  • There are a variety of LAWS that fluids obey
  • Need some definitions

2
Density
  • Regardless of form (solid, liquid, gas) we can
    define how much mass is squeezed into a
    particular space

3
Pressure
  • A measure of the amount of force exerted on a
    surface area

4
Pressure in a Fluid
  • The pressure is just the weight of all the fluid
    above you
  • Atmospheric pressure is just the weight of all
    the air above on area on the surface of the earth
  • In a swimming pool the pressure on your body
    surface is just the weight of the water above you
    (plus the air pressure above the water)

5
Pressure in a Fluid
  • So, the only thing that counts in fluid pressure
    is the gravitational force acting on the mass
    ABOVE you
  • The deeper you go, the more weight above you and
    the more pressure
  • Go to a mountaintop and the air pressure is lower

6
Pressure in a Fluid
Pressure acts perpendicular to the surface and
increases at greater depth.
7
Pressure in a Fluid
8
Buoyancy
Net upward force is called the buoyant
force!!! Easier to lift a rock in water!!
9
Displacement of Water
The amount of water displaced is equal to the
volume of the rock.
10
Archimedes Principle
  • An immersed body is buoyed up by a force equal to
    the weight of the fluid it displaces.
  • If the buoyant force on an object is greater than
    the force of gravity acting on the object, the
    object will float
  • The apparent weight of an object in a liquid is
    gravitational force (weight) minus the buoyant
    force

11
Flotation
  • A floating object displaces a weight of fluid
    equal to its own weight.

12
Flotation
13
Gases
  • The primary difference between a liquid and a gas
    is the distance between the molecules
  • In a gas, the molecules are so widely separated,
    that there is little interaction between the
    individual moledules
  • IDEAL GAS
  • Independent of what the molecules are

14
Boyles Law
15
Boyles Law
  • Pressure depends on density of the gas
  • Pressure is just the force per unit area exerted
    by the molecules as they collide with the walls
    of the container
  • Double the density, double the number of
    collisions with the wall and this doubles the
    pressure

16
Boyles Law
Density is mass divided by volume. Halve the
volume and you double the density and thus the
pressure.
17
Boyles Law
  • At a given temperature for a given quantity of
    gas, the product of the pressure and the volume
    is a constant

18
Atmospheric Pressure
  • Just the weight of the air above you
  • Unlike water, the density of the air decreases
    with altitude since air is compressible and
    liquids are only very slightly compressible
  • Air pressure at sea level is about 105
    newtons/meter2

19
Barometers
20
Buoyancy in a Gas
  • An object surrounded by air is buoyed up by a
    force equal to the weight of the air displace.
  • Exactly the same concept as buoyancy in water.
    Just substitute air for water in the statement
  • If the buoyant force is greater than the weight
    of the object, it will rise in the air

21
Buoyancy in a Gas
Since air gets less dense with altitude, the
buoyant force decreases with altitude. So helium
balloons dont rise forever!!!
22
Bernoullis Principle
23
Bernoullis Principle
  • Flow is faster when the pipe is narrower
  • Put your thumb over the end of a garden hose
  • Energy conservation requires that the pressure be
    lower in a gas that is moving faster
  • Has to do with the work necessary to compress a
    gas (PV is energy, more later)

24
Bernoullis Principle
  • When the speed of a fluid increases, internal
    pressure in the fluid decreases.

25
Bernoullis Principle
26
Bernoullis Principle
Why the streamlines are compressed is quite
complicated and relates to the air boundary
layer, friction and turbulence.
27
Bernoullis Principle
About PowerShow.com