Mid Term 1 Flashcards
What is a fluid?
Substance that flows
What are the three primary phases?
Solid liquid and gas
What primary phases are fluids?
Liquid and gas
What happens to fluids unders shear
They can’t resist, they flow
No slip condition
Wall fluid has velocity of wall due to viscosity
What differentiates gases from liquids as fluids
Liquid has a free surface and smaller atomic spacing and it feels the effects of gravity.
Gases have larger spacing and they feel a container.
Continuum
Fluids they composed of molecules that may be widely spaced. It is often idealized as a continuous homogeneous medium without voids. This allows properties to be treated as smoothly varying point functions without discontinuities.
λ
Mean average free path: average distance between molecules
When does the continuum hold?
When the Knudsen number is <0.01
Knudsen number formula
Kn(Knudsen#) = λ/L
Density
p = m/V
Specific volume
v = V/m or 1/p
Specific gravity
Also called relative density.
SG = p/ph20 at 4C
Specific weight
Weight density γ = pg
Pressure
Pressure is defined as a normal force exerted by a fluid per unit area.
Pressure= Fn/A
Pg
Pg= Pabs -Patm
(Pressure Gauge)
Pv
Pv = Patm- Pabs
(Pressure vaccume)
Pressure variation with depth
Influence pressure increases with depth due to the weight of the fluid above
Pascals law
In a confined incompressible fluid at rest, an external pressure applied to the fluid is transmitted, uniformly, and undiminished, and all directions throughout the fluid
Barometer
Barometer is a device used to measure the atmospheric pressure by converting a mercury filled tube into a mercury container that is open to the atmosphere
Manometer
Is the device used to measure pressure and gases or liquid systems. YouTube manometers may contain fluids like mercury, water, alcohol or oil with fluids like mercury commonly used for measuring high pressures.
Fluid Statics
Fluid static deals with problems associated with fluids at rest and is used to determine the forces acting on a floating or submerged body
Buoyancy
A solid body dropped into fluid will sink float or remain at rest at any point in the fluid, depending on its average density relative to the density of the fluid. This force is independent of the body shape, density and depth in the liquid.
How does buoyancy act
Buoyancy acts upward throughout the center of buoyancy which is the centroid of the displaced liquid
Surface tension
Surface tension minimizes the surface area for a given volume of fluid.
