Index

Arrhenius approximate law

Ver: 1

DESCRIPTION

For a generalized Newtonian fluid, the constitutive equation has the form

S = 2 * eta * D

where S is the extra-stress tensor, D is the rate of deformation tensor, and eta is the viscosity.

The temperature dependence of the viscosity is denoted by a function H(T), where T is the temperature.
H(T) comes as a factor in the viscosity law:

eta(g,T) = F(g)*H(T)

The approximate Arrhenius law is obtained as the first order Taylor expansion of the original Arrhenius law.
For the approximate Arrhenius law, the function H(T) is written as follows :

H(T) = exp [ - alpha * ( T - Talpha ) ] .

By default, alpha = 0 and Talpha = 0.
 

OPTIONS  
 -1   Upper level menu
  1   Modify  alfa   = 0.0000000E+00
  2   Modify  talfa  = 0.0000000E+00
NOTES A high value of the parameter alpha leads to strong non-linearities. A Picard iteration is recommended instead
of a full Newton iteration. In case the program diverges, an evolution scheme (on alpha) must be used.

The units for alpha and Talpha are:
 
parameter
mass
length
time
temperature
alfa
-
-
-
 -1
talfa
-
-
-
  1

SEE ALSO