click below
click below
Normal Size Small Size show me how
Exam 1
Fluid Mechanics
Term | Definition |
---|---|
fluid | a material that deforms continuously and permanently under the application of shear stress, no matter how small. Keep moving as long as force is applied. |
shear stress | force applied tangentially to the surface (Pa) (tau) |
shear rate | the rate at which fluid is sheared (s^-1) (sigma) |
bulk density | average density of a mixture of materials |
dynamic viscosity | the slope of the shear stress vs shear rate curve |
incompressible fluid | density is constant |
buoyant force | the weight of the fluid displaced by the object |
newtonian fluids | obey newton's law of viscosity |
pseudoplastic | become less viscous when shear is applied |
dilatant | become more viscous when shear is applied |
bingham plastics | hold their shape and behave as solids until a yield stress is exceeded, then they flow like a liquid |
viscosity | measure of resistance to flow |
surface tension | tendency for a liquid to take up a shape with the least possible surface area. caused by intermolecular attraction. requires work to break. |
archimedes principle | a partially or wholly submerged body is buoyed up by a force equal to the weight of the displaced object |
float | buoyant force > object weight |
sink | buoyant force< object weight |
manometer | helps us measure the pressure difference between two points by measuring the height difference of the fluid in each arm of the manometer |
bourdon tube | high pressure straightens the tube, which moves the dial |
diaphragm | contains a membrane that flexes up and down |
bellows | contains bellows that get compressed when pressure is applied |
block/plug flow | all the fluid in the pipe moves at the average velocity |
no slip condition | a fluid in direct contact with a solid surface will move at the same velocity of the surface. |
velocity profile | a plot of a fluids velocity at different radial points within a pipe |
reynolds number | inertial forces/viscous forces |
bernoullis principle | as the velocity of a fluid increases, the pressure of that fluid will decrease. |
venturi meter | a flow measurement device that uses a converging section of pipe to give an increased flow velocity and a corresponding decrease in pressure from which the flow rate can be deduced. |
discharge coefficient (Cv) | fudge factor that accounts for friction. |
ortifice meter | constriction caused by insertion of an ortifice plate rather than a gradual change in diameter. |
pitot tube | uses a change in pressure to determine velocity |
rotameter | uses bernoullis principle to measure flow; tapered tube with bob |