Index

modified Hershel-Bulkley 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 Hershel-Bulkley law, the function F(g) is written as follows :
 
F(g) = fac1 * [ 1 - exp( - 3*g/gcrit) ] / g
+ fac2 * (g/gcrit) (expo-1)

where fac1 and fac2 are material parameters, expo is a power index, and gcrit is a critical value of the shear-rate.

By default, fac1 = 1, fac2 = 1, expo = 1 and gcrit = 1.


OPTIONS

 
 -1   Upper level menu
  1   Modify  fac1    = 1.0000000E+00
  2   Modify  fac2    = 1.0000000E+00
  3   Modify  expo    = 1.0000000E+00
    4   Modify  gcrit   = 1.0000000E+00
NOTES In many situations, the use of a Picard iteration for the viscosity is recommended instead of a full Newton iteration.
An evolution scheme can also be used.

The units for g and the prameters fac1, fac2, expo and gcrit are :
 
 parameter
mass
length
time
temperature
g, gcrit
-
-
-1
 -
fac1
1
-1
-2
 -
fac2
1
-1
-1
 -
expo
-
-
-
 -

SEE ALSO