Index

FENE-P model

Ver: 1
 

DESCRIPTION

For the FENE-P model, the extra-stress tensor T can be written as
  T = T1 + T2


where T1 and T2 are tensors which obey the following constitutive equations :
 

T1 = visc1/trelax*[A/(1-trA/3/Lsqrd)-I/(1-1/Lsqrd)]

A/(1-trA/3/Lsqrd)+trelax*Aup=I/(1-1/Lsqrd)

T2 = 2 * visc2 * D
 

 Here, D is the symmetric part of the velocity gradient tensor, trelax is the relaxation time,
visc1 and visc2 are partial shear viscosities, Lsqrd is the square of the length ratio, and the
subscript "up" denotes the upper-convected derivative operator.
  visc1 = (1-ratio)*visc
visc2 = ratio*visc


The parameter ratio of the Newtonian viscosity to the total shear viscosity is defined by:
 

ratio = visc2 / ( visc1 + visc2 )


The default values of trelax, visc and Lsqrd are unity; the default value of ratio is zero.

Selecting an option allows the user to modify the corresponding material parameter.

  OPTIONS
 
 -1
   Upper level menu
  1
   Modification of visc
  2
   Modification of trelax
  3
   Modification of Lsqrd
  4
   Modification of ratio
NOTES A large relaxation time leads to strong non-linearities. The use of a non-linear strategy is recommended
for increasing this parameter : the current task should, therefore, be of the pseudo-evolution type.

The user should be aware of the system of units, if dimensional values are used.

The units for the material parameters, as well as for T and D are :
 
parameter
mass
length
time
temperature
trelax
-
-
 1
 -
visc
1
-1
-1
 -
ratio
-
-
-
 -
Lsqrd
-
-
-
-
T
1
-1
-2
 -
D
-
-
-1
 -

 SEE ALSO