For a generalized Newtonian fluid, the constitutive equation has the form
 | (6–5) |
where 
is the extra-stress tensor, 
is the rate-of-deformation tensor, and 
is the viscosity, which can depend upon both the second
invariant of 
and the temperature 
.
The general form for the viscosity 
is written as
 | (6–6) |
where 
is the local shear rate. Therefore, 
and 
represent the shear-rate and temperature dependence of the
viscosity, respectively.
To specify the function 
, you will click the Shear-rate dependence of
viscosity menu item in the Material Data
menu
Shear-rate dependence of viscosity
and to specify the function 
, you will click the Temperature dependence of
viscosity menu item.
Temperature dependence of viscosity
See Non-Automatic Fitting and Automatic Fitting for information about where and how the material data specification occurs in the non-automatic and automatic fitting procedures, respectively.
See Shear-Rate Dependence of Viscosity and Temperature Dependence of Viscosity for details about the parameters and characteristics of each fluid model.