Index

Temperature dependence of viscosity

Ver: 2
 

DESCRIPTION

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

S = 2 * eta * D

where S is the extra-stress tensor, eta is the viscosity, and D is the rate of deformation tensor. The viscosity may depend upon both the second invariant of D and the temperature T.

The general form for the viscosity h is written as

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

or

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

where both functions F(g) and H(T) denote the shear-rate and the temperature dependence of the viscosity, respectively. In the first case, the temperature scales the viscosity, while the time-temperature equivalence is introduced in the second case by also scaling the shear rate.

The present menu modifies H(T). By default, there is no temperature dependence of the viscosity. The current selection is marked '>'.

  OPTIONS
 
-1 
 Upper level menu
1 
 No temperature dependence
 No temperature dependence of the viscosity :  H(T) = 1
2 
 Arrhenius approximate law
3 
 Arrhenius law
4 
 Arrhenius approximate shear stress law
5 
 Arrhenius shear stress law
6 
 Mixed dependence
This is the only temperature dependence available when a 'Log-Log law' has been chosen for the shear-rate dependence. 
It is even mandatory.
7 
 Fulcher dependence
8 
 WLF dependence
9 
 WLF shear stress dependence
NOTES A non-linear strategy might be required with laws 2 or 3.   SEE ALSO