Fluids Flashcards
density (p)
p=m/V
density of water
1 g/cm^3 or 100 kg/m^3
Buoyancy (Fg)
Fg=pVg
specific gravity (SG)
p/1g/cm^3
pressure(P)
P=F/A
pascal
unit of pressure
1 N/m^2
presssure unit conversions
1.013E5 Pa=760mmHg=760 torr=1 atm
Absolute pressure
P=Po+pgz
Po=presssure at surface
z=depth
gauge pressure
Pgauge=(Po+pgz)-Patm
Pascals principle
P=(F1/A1)=(F2/A2)
archimedes principle
Fbuoy=(pfluid)(Vdisplacedfluid)(g)=(pfluid)(Vsubmerged)(g)
viscosity
resistance of a fluid to flow
viscous drag
increased with increased viscosity; air resistance
inviscid
no viscosity
laminar flow
layers of fluid that flow parallel to each other
Poiseuille’s law
Q=(pi)r^4ΔP/(8nL)
Q=flow rate
n=viscosity
turbulent flow
rough and disorderly
eddies
swirls of fluid of varying size occurring typically on the downstream side of an obstacle
critical speed
turbulence can arise when the speed of fluid exceeds this speed
boundary layer
when critical speed is exceeded, fluid demonstrates complex flow patterns and laminar flow occurs only in thin layer of fluid adjacent to the wall
critical speed calculation (vc)
vc=Nn/pD
N=constant called reynolds number
n= viscosity of the fluid
p= density
streamline
indicate pathway follows by tiny fluid elements
flow rate
constant for closed system; volume/time
linear speed
measure of linear displacement of fluid particles in a given amount of time
continuity equation
Q=v1A1=v2A2
Q=flow rate
v=linear speed
A=areas
Bernoulli’s equation
(P+1/2pv^2+pgh)1=(P+1/2pv^2+pgh)2
