Exam 2 Flashcards
(27 cards)
As the pressure of a compressible fluid decreases, does the velocity increase or decrease?
Increases
What is the Mach number range for an incompressible fluid? What chapter contains the equations for this?
Mach 0-0.3
Chapter 2
What is p1/p2 range for a compressible fluid? What chapters problems will you use?
P1/p2 > 2
Chapter 3
What is the Mach number range for a compressible fluid?
Mach > 0.3
What is the pressure range for an incompressible fluid?
P1/P2 is 0-2
What is Mach number?
Velocity of fluid / Velocity of sound of Fluid
(U/C)
What are Bingham plastics, list some
The material behaves like a solid until a certain required yield stress is exceeded, then the material begins to flow with a viscosity similar to a Newtonian fluid.
Examples are : toothpaste, Peanut butter
What are dilatants (shear thickening behavior), list some examples
At low shear rates, the material behaves like a fluid, but as the shear rate increases, the particles within the material start to interact more strongly, leading to an increase in viscosity and making the material act more like a solid
Ex. Oobleck, wet beach sand
What are pseudo plastics (shear thinning behavior), give examples
Flow immedietly but The viscosity decreases as the shear rate increases. When force is applied these materials become less resistant to flow and become “thinner”
Examples: paint, paper pulp, ketchup
Define Adiabatic
No heat exchange to the surroundings, all the energy changes are due to work. Change in temperature within the system unless perfectly insulated.
Define isothermal
The system is in equilibrium with its surroundings, heat is exchanged to maintain a constant temperature.
What makes something compressible?
The compressibility of gases is a result of their low density and large mount of empty space between molecules.
What makes something incompressible.
Particles are tightly packed and resist being squeezed
Which NNF does this Describe?
for these fluids shear stress increases as shear rate increases
Dilatants (shear-thickening fluids)
Which NNs does this describe?
these fluids exhibit a yield stress, below a certain shear rate, they behave like solids, and above it they flow like a fluid
Bingham plastics
Which NNs does this describe?
for these fluids, shear stress decreases as shear rate increases
Psuedoplastics (shear-thinning)
What is the graph behavior of a pseudoplastic (shear-thinning)
The curve is concave with shear stress decreasing at higher shear rates
What is the graph behavior of shear-thickening fluilds (Dilatants)
The curve is concave upwards, with shear stress increasing at higher shear rates
What is the graph behavior of Bingham plastics?
The curve has a distinct yield point, once the shear stress exceeds the yield stress, the fluid starts to flow
How do you solve for mass flowrate? (Ch.3)
Mass flowrate = G x area
What is G and what are its units
G is the mass velocity its units are kg/ m^2 x s
What are Viscoelastic NNs? Give examples
Materials which combine the elastic properties of solids with the flow behavior of fluids
Examples: Saliva, biological fluid, concentrated tomato soup, bread dough
Rheopectic examples
Stir vigorously and it freezes
Examples bentonite clay
Thixotropic examples
Shake it and it thins , let it sit and it thickens
Example: paints, printing inks, oil drilling mud
