Lecture 1-2 Flashcards
Fluids are
substances in the liquid or gas phase
Normal stress is
force on surface per unit area, orthognal to the plane/normal component
Shear stress is
force on a surface per unit area, parrallel to the plane/tangential component
Pressure is
normal stress in fluid at rest
Solids resist an applied shear stress by
deforming
Fluids —- —— under applied shear stress
deform continuously
Laminar flow is
highly ordered fluid motion, organised by smooth layers of fluid
Turbulent flow is
random chaotic fluid motion characterised by velocity fluctuations
Transitional flow is
a mix of laminar and turbulent flow
Re =
ρ V L / µ
fluid density x Volume x characteristic length / fluid viscosity
Reynold’s number
A laminar flow is characterised by a —- µ and —- V
high, low
A turbulent flow is chracterised by a —- μ and a —- V.
low, high
Intensive fluid properties are … 3 egs
properties that are independent of the mass of the fluid in a system
pressure temperature density
Extensive fluid properties are … 3 egs
properties that are dependent on the amount of fluid in the system
volume momentum energy
Specific fluid properties are
extensive fluid properties per unit mass
Specific energy =
Specific volume =
energy per unit mass
volume per unit mass
A control volume is
a small selected region in a space which represents the behaviours of the whole system
Density is
SI units
mass per unit volume
kg m^-3
SI units specific volume
m^3 kg^-1
Specific weight is
SI units
Weight per unit volume
N/m^3
Density and volume have what sort of relationship
Inversely proportional
Coefficient of compressibility or bulk modulus measures
the relative change of density or volume for a given pressure change (at a constant temp)
Coefficient of compressibility is represented with
small K
small K = (both density and volume)
Coefficient of compressibility =
d P / ( d ρ / ρ )
change in pressure / (change in density / initial density)
- d P / ( d V / V )
- change in pressure / (change in volume / initial volume)
Coefficient of volume expansion measures
the relative change of density or volume for a given temperature change (at P = 0)
Coefficient of volume expansion is represented with
β
β = (volume and density)
Coefficient of volume expansion =
(d V / V) / d T
(change in volume / initial volume) / change in temp
- (d ρ / ρ) / d T
- (change in density / initial density) / change in temp
Dynamic viscosity measures
resistance of deformation of a fluid as a ratio of shear stress and strain rate
Dynamic viscosity is represented with a
μ
Corn flour is an example of a —– fluid
non-newtonian fluid
Honey is an example of a —– fluid
newtonian fluid
Strain in dynamic viscosity = deformation =
change in distance of top plate / the distance bwteen the two plates
