Physics Flashcards
Yield stress
is the initial stress that must be overcome before it will begin to flow
Yield Strain
the deformation, resulting from the applied stress, at which flows starts
Newtonian Fluids
( ideal Viscous) have the same viscosity at low shear rates as at high shear rates ( water, milk olive oil)
Relation between the sheer stress and the strain rate is linear
Non-Newtonian Fluid
have different viscosity at different shear rates ( ketchup, mayo)
relation between the sheer stress and the strain is nonlinear, sometimes time- dependent
Pseudoplastic
shear thinning
Dilatant
shear thickening
Thermal conductivity
is the measure of the ability of a material to conduct heat
Thermal diffusivity
a measure of the ratio of the ease with which material can transmit heat to the ease with which it can store heat
Plasticity
describes a material that returns to their rest shape after applied stress
Rheometry
refers to the technique used to determine flow of matter under applied stress
texture, consistency and flow properties of food
Viscometers( rheometers)
measure several properties
why is rheology important
sensory perception, processing and stability
On- line
sample stream, pumped back, gear pump
in- line
process vessel ( Adjusted immediately)
Off-line
lab ( slow and costly )
