UFLUIDLEAKOFF

User subroutine to define the fluid leak-off coefficients for pore pressure cohesive elements.

can be used to define the fluid leak-off coefficients for pore pressure cohesive elements;
is called at all material calculation points of elements for which the material definition contains user-defined leak-off coefficients; and
can include material behavior dependent on field variables or state variables.

The following topics are discussed:

User subroutine interface
Variables to be defined
Variables passed in for information

User subroutine interface

      SUBROUTINE UFLUIDLEAKOFF(PERM,PGRAD,DN,P_INT,P_BOT,P_TOP,
     1 ANM,TANG,TIME,DTIME,TEMP,DTEMP,PREDEF,DPRED,C_BOT,C_TOP,
     2 DC_BOT,DC_TOP,STATEV,NSTATV,NOEL,NPT,KSTEP,KINC)
C
      INCLUDE 'ABA_PARAM.INC'
C
      CHARACTER*80 CMNAME
      DIMENSION PERM(2),PGRAD(2),ANM(3),TANG(3,2),TIME(2),PREDEF(1),
     1 DPRED(1),DC_BOT(3),DC_TOP(3),STATEV(NSTATV)
   

      user coding to define C_BOT, C_TOP, DC_BOT, and DC_TOP

      RETURN
      END

Variables to be defined

C_BOT: $C_{b o t}$ , fluid leak-off coefficient on the bottom side of a pore pressure cohesive element.
C_TOP: $C_{t o p}$ , fluid leak-off coefficient on the top side of a pore pressure cohesive element.
DC_BOT(1): $\partial C_{b o t} / \partial d$ , where d=DN.
DC_BOT(2): $\partial C_{b o t} / \partial p_{i n t}$ , where $p_{i n t}$ =P_INT.
DC_BOT(3): $\partial C_{b o t} / \partial p_{b o t}$ , where $p_{b o t}$ =P_BOT.
DC_TOP(1): $\partial C_{t o p} / \partial d$ , where d=DN.
DC_TOP(2): $\partial C_{t o p} / \partial p_{i n t}$ , where $p_{i n t}$ =P_INT.
DC_TOP(3): $\partial C_{t o p} / \partial p_{t o p}$ , where $p_{t o p}$ =P_TOP.
STATEV(NSTATV): An array containing the values of the solution-dependent state variables. You define the meaning of these variables. These are passed in as the values at the beginning of the increment and must be returned as the values at the end of the increment. The size of the array is defined as described in Allocating space.

Variables passed in for information

PERM(1): Fluid permeability.
PERM(2): The derivative of fluid permeability with regard to the opening.
PGRAD(1): The first component of internal pressure gradient.
PGRAD(2): The second component of internal pressure gradient.
DN: The relative opening of the element.
P_INT: Internal pressure.
P_BOT: Bottom pressure.
P_TOP: Top pressure.
ANM: Normal vector directed from the bottom face toward the top face.
TANG: Tangent direction vectors.
TIME(1): Value of step time at the beginning of the current increment.
TIME(2): Value of total time at the beginning of the current increment.
DTIME: Time increment.
TEMP: Temperature at the start of the increment.
DTEMP: Increment of temperature.
PREDEF: Array of interpolated values of predefined field variables at this point at the start of the increment, based on the values read in at the nodes.
DPRED: Array of increments of predefined field variables.
NSTATV: Number of solution-dependent state variables that are associated with this material type (defined as described in Allocating space).
NOEL: Element number.
NPT: Integration point number.
KSTEP: Step number.
KINC: Increment number.