Lesson 2: Properties of Fluids Flashcards
any characteristic of a system
property
independent of the mass of the system; (ex. temperature, pressure, density)
intensive property
depend on the size; (ex. mass, volume)
extensive property
extensive properties per unit mass; specific volume, total energy
specific property
The state of a simple compressible system is completely specified by two independent, intensive properties
state postulate
equation that relates the pressure, temperature, and density of a substance Ex: ideal gas equation of state
equation of state
temperature at which pure substance changes phase (at 1 atm, the saturation temperature of water is 100 degrees Celsius)
saturation temperature
pressure at which a pure substance changes phase
saturation pressure
pressure exerted by its vapor in phase equilibrium with its liquid at a given temperature
vapor pressure
pressure of a gas or vapor in a mixture with other gases
partial pressure
is the sum of the partial pressure of dry air and the partial pressure of water vapor
atmospheric pressure
what increases with vapor pressure?
temperature
vapor bubbles collapse as they are swept away from low-pressure regions, generating highly destructive, extremely high-pressure waves
cavitation
sum of all numerous forms of energy of a system
total energy, E
by the contact (or wetting) angle ϕ – angle that the tangent to the liquid surface makes with the solid surface at the point of contact
microscopic energy
sum of all microscopic forms of energy (U)
internal energy
energy related to motion and the influence of some external effects such as gravity, magnetism, electricity, and surface tension.
macroscopic energy
energy that a system possess as a result of its motion
kinetic energy
energy that a system possess as a result of its elevation in a gravitational field
potential energy
a simple compressible system is absent of what?
magnetic, electric, and surface tension
what does it mean if k value is large
large pressure is needed to cause a fractional change in volume (incompressible)
The force a flowing fluid exerts on a body in the flow direction; depends on viscosity
drag force
characteristics of newtonian fluids
- Rate of deformation is linearly proportional to shear stress
- Water, air, gasoline, oil
- Plot of shear stress vs rate of deformation (velocity gradient) is a straight line
viscosity unit, equivalent to 0.1 Pa s
poise
Non-linear relationship between shear stress and rate of deformation
non-newtonian fluids
apparent viscosity increases with the rate of deformation
dilatant (shear thickening fluids)
apparent viscosity decreases with the rate of deformation
Pseudoplastic (shear thinning fluids)
substances that resists a finite shear stress and thus behave as a solid, but deform continuously when the shear stress exceeds the yield stress and behave as a fluid
bingham plastic
