T2:07 - Into to fluid dynamics Flashcards
(24 cards)
What defines a fluid?
A substance that deforms continuously under shear forces.
Which states of matter are considered fluids?
Liquids and gases.
How do liquids and gases differ?
Liquids are incompressible with fixed volume; gases are compressible and expand indefinitely.
What is Newton’s law of viscosity?
τ = μ (dv/dy), where μ is dynamic viscosity.
What is mass density (ρ)?
Mass per unit volume of a substance.
What is specific weight (w)?
Weight per unit volume, w = ρg.
What is specific gravity (σ)?
The ratio of a substance’s density to that of water at 4°C.
What is dynamic viscosity (μ)?
A measure of a fluid’s resistance to flow.
What is kinematic viscosity (ν)?
The ratio of dynamic viscosity to mass density: ν = μ / ρ.
What is a pathline?
The actual path followed by a fluid particle.
What is a streakline?
The instantaneous position of all particles that have passed through a specific point.
What is a streamline?
A curve tangent to the velocity vector of the flow at a given instant.
What is a streamtube?
A bundle of streamlines forming an imaginary pipe through which fluid flows.
Define steady uniform flow.
No change in velocity or area with time or position.
Define steady non-uniform flow.
Velocity and area vary by position but not time.
Define unsteady uniform flow.
Velocity is uniform at a given time but changes over time.
Define unsteady non-uniform flow.
Velocity and area vary with both time and position.
What is a boundary layer?
Region near a surface where fluid velocity changes from zero to free stream.
What is laminar flow?
Smooth, orderly flow with parallel fluid layers.
What is turbulent flow?
Chaotic flow with mixing and velocity fluctuations.
What is Reynold’s number (Re)?
Re = ρvD / μ, a dimensionless number indicating flow type.
Re < 2100 indicates what type of flow?
Laminar flow.
Re > 4000 indicates what type of flow?
Turbulent flow.
What does the transitional Re range 2100–4000 represent?
Mixed behavior between laminar and turbulent.
