Power law (liquid)
In the material laws of rheology ( flow laws ), non-linear approximation approaches according to power laws are often made in order to be able to describe the behavior of non-Newtonian liquids .
The general law of power , also called the Herschel-Bulkley relation , is:
with the yield point .
With the parameters one obtains the two-parameter flow law according to Ostwald and de Waele :
,
there are:
- : Shear stress (see stress (mechanics) )
- k : consistency
- : Shear rate
- n : flow exponent or flow index.
The flow exponent n characterizes the deviation from Newtonian behavior:
- n <1: pseudoplastic (shear thinning) and pseudoplastic ( plasticity )
- n = 1: Newtonian
- n > 1: dilatant (shear thickening).