fluid mechanics

fluid

a substance that deforms continuously when acted on by a shearing stress of any magnitude

high viscosity

slow flow, thick

low viscosity

fast flow, thin

viscosity

a fluids thickness and resistance to flow

relationship between shear stress, viscosity, and rate of strain

Describes how a fluid deforms under applied stress.

newtonian fluids

fluids that have a linear relationship with stress and rate of strain

non-newtonian fluids

fluids that do not have a linear relationship. viscosity changes as you apply shear stress

absolute pressure

measured relative to a perfect vacuum. cannot be lower than 0 in abs.

gage pressure

measured relative to current local atmospheric pressure

Reynolds number

describes the rate of flow. it is dimensionless.

assumptions of pressure

fluid is at rest, not moving or accelerating.

fluid is incomprehensible. density will not change without elevation or temperature

pressure at a point

comes from every direction, is a scalar

always normal to the surface

archimedes principle

the upward buoyant force acting on a submerged or floating object equals the weight of the fluid that the object displaces

principles of buoyancy

a buoyant force is exerted by a fluid on a body partially or completely submerged

buoyant force is equal to the weight of the fluid displaced by the body

the buoyant force acts upward through the centroid of the displaced volume

incompressible flow

density does not change over time