fluidsandtheirproperties.pptx for secondary

fluidsandtheirproperties.pptx for secondary

• 1.
  FLUIDS AND THEIR PROPERTIES Prof.Fabian R
• 2.
  1.WHAT IS FLUID? Fluid is a substance that is capable of flowing. It has no definite shape of its own. It assumes the shape of its container.  Both liquids and gases are fluids.  Examples of fluids are : i. water ii. milk iii. kerosene iv. petrol v. emulsions etc.
• 3.
  2. TYPES OFFLUIDS  Fluids can be classified into five basic types. They are:  Ideal Fluid  Real Fluid  Pseudo-plastic Fluid  Newtonian Fluid  Non-Newtonian Fluid
• 4.
  2.1 IDEAL FLUID An Ideal Fluid is a fluid that has no viscosity.  It is incompressible in nature.  Practically, no ideal fluid exists.
• 5.
  2.2 REAL FLUID Real fluids are compressible in nature. They have some viscosity.  Real fluids implies friction effects.  Examples: Kerosene, Petrol, Castor oil
• 6.
  2.3 PSEUDO-PLASTIC FLUID A fluid whose apparent viscosity or consistency decreases instantaneously with an increase in shear rate.  Examples are: i. quick sand ii. ketch-up etc.
• 7.
  2.4 NEWTONIAN FLUID Fluids that obey Newton’s law of viscosity are known as Newtonian Fluids. For a Newtonian fluid, viscosity is entirely dependent upon the temperature and pressure of the fluid.  Examples: water, air, emulsions
• 8.
  2.5 NON-NEWTONIAN FLUIDS Fluids that do not obey Newton’s law of viscosity are non-Newtonian fluids.  Examples: Flubber, Oobleck (suspension of starch in water), Pastes, Gels & Polymer solutions.
• 10.
  3. PROPERTIES OFFLUIDS  Properties of fluids determine how fluids can be used in engineering and technology. They also determine the behaviour of fluids in fluid mechanics. They are:  Density  Viscosity  Surface Tension  Capillary Action  Specific Weight  Specific Gravity
• 11.
  3.1 DENSITY  Densityis the mass per unit volume of a fluid. In other words, it is the ratio between mass (m) and volume (V) of a fluid.  Density is denoted by the symbol ‘ρ’. Its unit is kg/m3 .
• 12.
  3.2 VISCOSITY  Viscosityis the fluid property that determines the amount of resistance of the fluid to shear stress.  It is the property of the fluid due to which the fluid offers resistance to flow of one layer of the fluid over another adjacent layer.
• 13.
  3.2.1 DYNAMIC VISCOSITY The Dynamic (shear) viscosity of a fluid expresses its resistance to shearing flows, where adjacent layers move parallel to each other with different speeds.
• 14.
  3.2.2 KYNEMATIC VISCOSITY The kinematic viscosity (also called "momentum diffusivity") is the ratio of the dynamic viscosity μ to the density of the fluid ρ.
• 15.
  3.3 SURFACE TENSION The property of fluids to resist tensile stresses on their surface is called as Surface Tension.
• 16.
  3.4 CAPILLARY ACTION Capillary action is the property of fluid to flow in a narrow spaces without assistance of and in opposition to external forces like gravity.  The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper and plaster, in some non-porous materials such as sand or in a cell.  It occurs because of intermolecular forces between the liquid and surrounding solid surfaces.
• 18.
  3.5 SPECIFIC WEIGHT Specific weight is the weight possessed by unit volume of a fluid. It is denoted by ‘w’. Its unit is N/m3 .  Specific weight varies from place to place due to the change of acceleration due to gravity (g).
• 19.
  3.6 SPECIFIC GRAVITY Specific gravity is the ratio of specific weight of the given fluid to the specific weight of standard fluid.  It is denoted by the letter ‘S’. It has no unit.