*DFLUX

Specify distributed fluxes in computational fluid dynamics and mass diffusion analyses and specify distributed fluxes and nonuniform concentrated fluxes in heat transfer analyses.

This option is used to apply distributed fluxes in fully coupled thermal-stress analysis. In Abaqus/Standard it is also used for heat transfer, coupled thermal-electrical, and mass diffusion analyses.

This page discusses:

See Also
In Other Guides
Thermal Loads
DFLUX
UMDFLUX

ProductsAbaqus/StandardAbaqus/Explicit

TypeHistory data

LevelStep

Optional parameters

AMPLITUDE

Set this parameter equal to the name of the amplitude curve that defines the magnitude of the distributed fluxes during the step (Amplitude Curves).

If this parameter is omitted for uniform flux types in an Abaqus/Standard analysis, the reference magnitude is applied immediately at the beginning of the step or linearly over the step, depending on the value assigned to the AMPLITUDE parameter on the STEP option (Defining an Analysis). If this parameter is omitted in an Abaqus/Explicit analysis, the reference magnitude is applied immediately at the beginning of the step.

In Abaqus/Standard for nonuniform distributed fluxes of type BFNU and SnNU the flux magnitude is defined in user subroutine DFLUX and AMPLITUDE references are ignored. In Abaqus/Explicit for nonuniform distributed fluxes of type BFNU and SnNU the flux magnitude is defined in user subroutine VDFLUX and AMPLITUDE references are passed in the user subroutine.

In Abaqus/Standard for nonuniform concentrated fluxes of type MBFNU the flux magnitude is defined in user subroutine UMDFLUX and AMPLITUDE references are passed in the user subroutine.

OP

Set OP=MOD (default) for existing DFLUXs to remain, with this option modifying existing fluxes or defining additional fluxes.

Set OP=NEW if all existing DFLUXs applied to the model should be removed.

Data lines to define a distributed flux

First line

  1. Element number or element set label.

  2. Distributed flux type label (see About the Element Library).

  3. Reference flux magnitude (units of JT−1L−2 for surface fluxes and JT−1L−3 for body fluxes). It is needed for uniform fluxes only. If this value is given for nonuniform fluxes, it will be passed into user subroutine DFLUX, where the actual flux magnitude is defined.

    In heat transfer analysis the units are JT−1L−2 for surface fluxes and JT−1L−3 for body fluxes. In mass diffusion analysis the units are PLT−1 for surface fluxes and PT−1 for body fluxes.

Repeat this data line as often as necessary to define distributed fluxes for different element surfaces.

Data lines to define a nonuniform concentrated flux inside the user subroutine UMDFLUX

First line
  1. Element set label.
  2. Distributed flux type label (see About the Element Library).
  3. Leave this entry blank (any value entered here will be ignored).
  4. Table collection name or blank if no table collection is used.

Repeat this data line as often as necessary to define distributed fluxes for different element surfaces.