1. Mécanique des Fluides

• Fluid Mechanics is the study of forces and motions in fluids like water, oil, and milk
• Subdivisions and applications of fluid mechanics include:

  • Hydraulics: flow of water in rivers, pipes, canals, pumps, turbines
  • Aerodynamics: flow of air around airplanes, rockets, structures
  • Meteorology: flow of the atmosphere
  • Particle dynamics: flow of fluids around particles, interaction of particles and fluids
  • Hydrology: flow of water and waterborne pollutants in the ground
  • Reservoir mechanics: flow of oil, gas, and water in petroleum reservoirs
  • Multiphase flow: coffee percolators, oil wells, carburetors, combustion chambers
• Fluid mechanics deals with the motion and equilibrium of liquids and gases
• Basic ideas in fluid mechanics are based on:

  1. Principle of the conversion of mass

  2. First law of thermodynamics

  3. Second law of thermodynamics

  4. Newton’s law of motion (F = ma)
• Properties of Fluid:

  • Density varies with temperature and pressure
  • Density of water decreases with temperature increase
  • Density of water at 1 atm and 4 ℃ is 1000 kg/m3
• Specific weight:

  • Weight of fluid per unit volume
  • Specific weight of water at 1 atm and 4 ℃ is 9.81 kN/m3
• Viscosity:

  • Property determining resistance to shearing force
  • Coefficient of dynamic viscosity or absolute viscosity, 𝜇, relates shear stress to velocity
• Kinematic Viscosity, 𝜈:

  • Ratio of absolute viscosity (𝜇) to density (𝜌)
  • Viscosities of liquids decrease with temperature increase
  • Absolute viscosity of gases increases with temperature increase
• Kinematic Viscosity, 𝜈:

  • Ratio of absolute viscosity (𝜇) to density (𝜌)
  • Viscosities of liquids decrease with temperature increase
  • Absolute viscosity of gases increases with temperature increase
• Surface Tension:

  • Phenomenon at the surface of a liquid in contact with another phase
  • Molecule in liquid interior under attractive forces
• Vapor Pressure:

  • Partial pressure created by vapor molecules during evaporation
  • Depends on temperature and increases with it
• Pressure:

  • Compressive stress in fluid
  • Atmospheric pressure: 14.7 PSI or 101,325 Pa
• Force, Mass, and Weight:

  • Mass indicates the amount of matter
  • Weight is the force due to gravity's acceleration
• Unit Systems:

  • SI System, Imperial System, American System, Metric System
  • Most of the world uses the metric (SI) system
• Techniques in Converting:

  1. Treat dimensions as algebraic quantities

  2. Multiplying or dividing by 1 does not change value

  3. Any dimensioned equation can be converted to 1=1 by dividing through by either side