FLUID

FLUID

A.understanding Fluid

Various kinds of understanding of the fluid that is:

· Fluid is a substance that can change shape continuously when exposed to shear stress although relatively small. The shear force is the force components that offend the surface and when divided by the surface area becomes the average shear stress on the surface.

· Fluid is a group that is composed of molecules with large separation distances for gas and small for liquids. The molecules are not tied to a grid, but each move freely against each other.

· Fluid is an object that can change shape continuously since the frictional forces working against him.

· Fluid is a substance that can flow that has particles that easily move and change shape without mass separation. Resilience fluid to deformation is very small so that the fluid can easily follow the shape of the room's shape.

B. Various Fluid

Fluid (flow agent) is a substance that can flow, for example, liquids and gases. Fluid can be classified into two types, namely: fluid static and dynamic fluid.

1). fluid Static

HYDROSTATIC PRESSURE

Hydrostatic pressure (Ph) is the pressure exerted on a liquid base plane place.

HYDROSTATIC PARADOX

The force acting on the basis of a vessel does not depend on the shape of the vessel and the amount of liquid in the vessel, but it depends on a broad basis of vessel (A), height (h) and the density of the liquid (r) in the vessel.

 Ph = r g h

 Pt = Po + Ph

 F = P = r g h A V

 r = density of liquid

 h = height of liquid on the surface

 g = acceleration due to gravity

 Pt = total pressure

 Po = outside air pressure

                                                  (Equation 1.a)

LEGAL PASCAL

F2

A2

F1

A1

Pressure exerted on a liquid is sealed, forwarded to every part of the liquid and the walls of a liquid substance as great.

p1 = p2

                                                  (Equation 1.b)

LEGAL ARCHIMEDES
Objects in the liquid will experience a reduction in weight by weight of liquid displaced.
Three state bodies in liquid:
  a. drowning: W> Fa b> z

  b. float: W = Fa b = z

  c. Floating: Fa> W b.V = z.V '; b <z

      (Equation 1.c)
W = weight of the object
Fa = force upward = z. V '. g
b = mass of the object
z = mass of fluid
V = volume of the object
V '= volume of objects that are in fluid
Due to the upward force (Fa), of body weight in liquids (Wz) would be reduced to:
Wz = W - Fa
Wz = heavy objects in liquids

SURFACE TENSION
The surface tension () is a large force (F) experienced on the surface of the liquid unity length (l)
  = F / 2l (Equation 1.d)

capillarity
Capillarity phenomenon is rising or falling liquid (y) in the capillary tube is inserted partially into a liquid for directional adhesion and cohesion.
       y = 2 cos  /  g r (Eq 1.e)
 y = increase / decrease in liquid in the pipe (m)
 = surface tension (N / m)
 = contact angle (degrees)
 p = density of the liquid (kg / m3)
 g = acceleration of gravity (m / s2)
 r = radius of the capillary tube (m)

2) Fluid Dynamic
Ideal Fluid nature:
- Can not be pressed (fixed volume due to pressure)
- Can move without friction
- Has a stationary flow (alirnya line is fixed for each particle)
- The speed of the particles at the same cross-section




LEGAL Bernoulli
This law is applied to the liquid flowing at different speeds in a pipe.
 P +  1/2  g Y + v2 = c
  P = pressure
  1/2  v2 = kinetic energy
   g y = Potential Energy
 ] tiap unit
       time
                                                              (Equation 1.f)
FAST FLOW (AIR DISCHARGE)
Fast flow (Q) is the volume of fluid displaced per unit time.
Q = A. v
A1. v1 = A2. v2
v = velocity of fluid (m / s)
A = cross-sectional area through which the fluid
For liquids flowing through a hole in the tank, then great speed can always be derived from Bernoulli's Law, namely:
 v = √ (2gh) h = depth of the hole from the surface of the liquid
                                                              (Equation 1.g)
Example:
1. A water pool walled rectangle with a length of 15 m, height 7,5m.Tentukanlah water pressure of 4.5 m below the surface of the water!
Answer:
P = . g. h = 103. 10. 4.5
P = 4,5.104 N / m2

2. Water flows along a horizontal pipe, the cross section is not as great. In a place with water velocity of 35 cm / sec the pressure was 1 cmHg. Determine the pressure in the pipe where the water flow velocity of 65 cm / sec. (G = 980 cm / s2)!
Answer:
P1 = 1 cmHg = 1.13,6.980 dyne / cm2
P1 = 13328 dyne / cm2
v1 = 35 cm / sec; v2 = 65 cm / sec
Bernoulli's principle:
P1 + pgy1 + 1 / 2 v12 = P2 + gy2 + ½  v22
Because y1 = y2 (horizontal pipe), then:
P1 - P2 = 1/2  (V22 - V12)
P1 - P2 = 1/2 1 (652 352)
P1 - P2 = 1/2 3000
P1 - P2 = 1500 dyne / cm2
So:
P2 = P1 - 1500
P2 = 13328-1500
P2 = 11828 dyne / cm

P2 = 0.87 cmHg