Fluid Mechanics Overview

Ideal and Real Fluids

• Ideal fluids are theoretical constructs that lack viscosity and are incompressible.
• Real fluids possess viscosity, which is the resistance to flow.
• Density, viscosity, and surface tension are crucial properties of real fluids.

Types of Fluid Flow

• Steady flow: Velocity, pressure, and other characteristics remain constant over time at a specific point.
• Unsteady flow: Velocity and other characteristics change with time at a specific point.
• Uniform flow: Velocity is the same at all points in the fluid at a given instant.
• Non-uniform flow: Velocity varies at different points in the fluid at a given time.
• Laminar flow: Individual particles follow well-defined paths without crossing or intersecting.
• Turbulent flow: Particles follow irregular paths that cross and re-cross each other.
• Compressible flow: Density remains relatively constant as the fluid moves.
• Incompressible flow: Density varies due to pressure changes.
• Rotational flow: Fluid particles rotate about their axis while flowing along a streamline.
• Irrotational flow: Fluid particles do not rotate about their axis while flowing along a streamline.
• One-dimensional flow: Velocity is a function of time and one space coordinate. Occurs in long, straight pipes or between parallel plates.
• Two-dimensional flow: Velocity is a function of time and two space coordinates. Occurs in plane flows.
• Three-dimensional flow: Velocity is a function of time and three space coordinates.

Fluid Flow Illustrations

• Path lines: Tracks the path of a single particle over time.
• Streak lines: Shows the instantaneous positions of all particles originating from a specific point.
• Streamlines: Lines tangent to the velocity vector at every point, representing the instantaneous velocity direction of the fluid.
• Stream tube: A tube formed by streamlines, across which no fluid can pass.

Fluid Flow Equations

• Discharge or flow rate (Q): Amount of fluid passing through a section per unit time.
  • Volume flow rate (Q) = Av
  • Mass flow rate (M) = ρQ
  • Weight flow rate (W) = γQ
  • A: cross-sectional area
  • v: mean velocity
  • ρ: mass density
  • γ: weight density

Basic Laws of Fluid Flow

• Conservation of mass: States that mass can only be transformed, not created or destroyed.
  • In fluid flow, the amount of fluid entering a system equals the amount leaving, assuming no leaks or accumulation.
  • Represented by the continuity equation: 𝐴1𝑣1 = 𝐴2𝑣2
• First law of thermodynamics: States that energy can be transformed but not created or destroyed.
  • Energy in fluid flow exists in kinetic, potential, and internal forms.
  • Total energy remains constant but can convert between forms.
• Newton's second law: States that the resultant force acting on a system equals the rate of change of its momentum.

Energy and Heads of Fluids in Motion

• Energy: Ability to do work. In fluids, it exists as kinetic, potential, and pressure energies.
• Kinetic energy: Energy possessed by a mass due to its motion.
• Velocity head: Kinetic energy per unit weight (𝑣𝟐 𝟐𝒈)
• Potential energy: Energy possessed by a mass due to its position.
• Elevation head: Potential energy per unit weight (z)
• Pressure energy: Energy possessed by a fluid due to its pressure.
• Pressure head: Pressure energy per unit weight (P/γ)

Explore the concepts of ideal and real fluids, including their properties like viscosity and density. Understand the various types of fluid flow such as steady, unsteady, laminar, and turbulent flows. This quiz will test your knowledge of fluid dynamics principles.