CONCLUSION

Actually, we forget to introduce our group. We are The Six Sense. We from Section 1 for BFC 10403 fluid mechanic subject. From left ;

1. Nurul Aqillah Mubi
2. Siti Haziqah Muhamad
3. Nur Atiqah Dinie Mat Ariffin 
4. Zuhaida Taharudin 
5. Nur Rabiatul Adawiyah Maulat Rasid
6. Nurul Aainaa Asri 

The topic given for our group are properties of fluid and fluids in relative equilibrium.  

 So, here are the group members. A lot of thanks to all members for giving cooperation and help along the project. Thanks also to our fluid mechanics lecturer, Pn Aliza Ahmad for the guide in this project. 

Hope that this blog will help student in their research for fluid mechanic.

FLUIDS IN RELATIVE EQUILIBRIUM

PRESSURE

• Pressure is defined as a normal force exerted by a fluid per unit area. Pressure is defined as force perunit area, it has the unit of newtons per square meter (N/m2), which is called a pascal (Pa).
• The actual pressure at a given position is called the absolute pressure, and it is measured relative to absolute vacuum (i.e., absolute zero pressure)
• Most pressure-measuring devices, however, are calibrated to read zero in the atmosphere and so they indicate the difference between the absolute pressure and the local atmospheric pressure.This difference is called the gage pressure.
• Pressures below atmospheric pressure are called vacuum pressures and are measured by vacuum gages that indicate the differencebetween the atmospheric pressure and the absolute pressure.

VARIATION OF PRESSURE WITH DEPTH

• Pressure in a fluid increases with depth because more fluid rests on deeper layers, and the effect of this “extra weight” on a deeper layer is balanced by an increase in pressure.

• If we take point 1 to be at the free surface of a liquid open to the atmosphere where the pressure is the atmospheric pressure Patm, then the pressure at a depth h from the free surface becomes P2

• Pressure in a fluid at rest is independent of the shape or cross section of the container. It changes with the vertical distance, but remains constant in other directions. Therefore, the pressure is the same at all points on a horizontal plane in a given fluid.
• pressure at a point is same in all directions. This is Pascal's law. This applies to fluid at rest.

PRESSURE MEASUREMENT

1. MANOMETER

2. BAROMETER

• Atmospheric pressure is measured by a device called a barometer; thus, the atmospheric pressure is often referred to as the barometric pressure.

HYDROSTATIC FORCES

1. On submerged plane surfaces.

• A plate exposed to a liquid, such as a gate valve in a dam, the wall of a liquid storage tank, or the hull of a ship at rest, is subjected to fluid pressure distributed over its surface
• On a plane surface, the hydrostatic forces form a system of parallel forces, and we often need to determine the magnitude of the force and its point of application, which is called the center of pressure.

BUOYANCY AND STABILITY

• The force that tends to lift the body is called the buoyant force and is denoted by FB. The buoyant force is caused by the increase of pressure in a fluid with depth.

• For floating bodies, the weight of the entire body must be equal to the buoyant force, which is the weight of the fluid whose volume is equal to the volume of the submerged portion of the floating body. That is, of uniform density, its weight Wsalso acts through the centroid, but its

Properties of Fluids

A fluid may be defined broadly as a substance which deforms continuously when subjected to shear stress .  This fluid can be made to flow if it is acted upon by a source of energy. This can be made clear by assuming the fluid being consisted of layers parallel to each other and letting a force act upon one of the layers in a direction parallel to its plane. This force divided by the area of the layer is called shear stress. As long as this shear stress is applied the layer will continue to move relative to its neighboring layers.

A fluid is always a continuous medium and there cannot be voids in it. The properties of a fluid, e.g., density, may, however, vary from place to place in the fluid. In addition to shear force, fluid may also be subjected to compressive forces. These compressive forces tend to change the volume of the fluid and in turn its density. If the fluid yields to the effect of the compressive forces and changes its volume, it is compressible, otherwise it is incompressible .

a)  Density (ketumpatan)   

• density is highly variable in gases and increases nearly proportionally to the pressure level.

   

   

b) Specific Volume (isipadu tentu)

c) Relative Density (ketumpatan relatif)

• the ratio of the density of a substance to the density of some standard substance at a specified temperature (usually water at 4°C, for which density H2O  1000 kg/m3).  

d) Specific Gravity, SG (graviti tentu)

• the density of a substance is given relative to the density of the well-known substance.

e) Specific Weight (berat tentu)

f) Compressibility (kebolehmampatan)

• refers to the change in volume (V) of a substance that is subjected to a change in pressure on it.

g) Bulk Modulus, E (modulus pukal)

h ) Viscosity  (Kelikatan)   

  

• The internal resistance of a fluid to motion or the “fluidity,” and that property is the viscosity.
• The force a flowing fluid exerts on a body in the flow direction is called the drag force, and the magnitude of this force depends, in part, on viscosity  

• Fluids for which the rate of deformation is proportional to the shear stress are called Newtonian fluids   
• Water, air, gasoline, and oils (Newtonian fluids) Blood and liquid plastics (non-Newtonian fluids)  
• In one-dimensional shear flow of Newtonian fluids, shear stress can be expressed by the linear relationship 

i) Dynamic Viscosity  (Kelikatan dinamik) 

• defined as shear force per unit area 

                            Force/ Area       = Force x Time  =         Mass       

                       Velocity/ Distance         Area               Length x Area

j) Kinematic Viscosity  ( Kelikatan kinematik )

•  the ratio of dynamic viscosity to density 

k ) Surface Tension ( ketegangan permukaan )

• a drop of blood forms a hump on a horizontal glass!  
• a drop of mercury forms a near-perfect sphere and can be rolled just like a steel ball over a smooth surface!  
• water droplets from rain or dew hang from branches or leaves of trees! 

l) Capillary effect (Kererambutan)    

• Another interesting consequence of  surface tension is the capillary effect,which is the rise or fall of a liquid in a small-diameter tube inserted into the liquid.  
• This effect is usually expressed by saying that water wets the glass (by sticking to it) while mercury does not