Index

modified Cross 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 shear-rate dependence of the viscosity is denoted by a function F(g), where g is the shear-rate.

For the modified Cross law, the function F(g) is written as follows :

F(g) = fac / [ 1 + (tnat *g)]expom

where fac is the zero shear-rate viscosity, tnat is a time scale, and expom is a power index.

By default, fac = 1, and tnat = 0 and expom = 0.


OPTIONS

 
 -1   Upper level menu
  1   Modify  fac    = 1.0000000E+00
  2   Modify  tnat   = 0.0000000E+00
  3   Modify  expom  = 0.0000000E+00
NOTES A value for the parameter expom close to 1 leads to strong non-linearities. A Picard iteration is recommended instead
of a full Newton iteration in cases where expom is large. An evolution scheme can also be used, starting from expom=0
(Newtonian fluid) and decreasing expom.

The units for g and the parameters fac, tnat, and expom are :
 
parameter
mass
length
time
temperature
g
-
-
-1
 -
tnat
-
-
 1
 -
fac
1
-1
-1
 -
expom
-
-
-
 -

SEE ALSO