Products: ABAQUS/Standard ABAQUS/Explicit ABAQUS/CAE
A material's latent heat:
models large changes in internal energy during phase change of a material;
is active only during transient heat transfer, coupled thermal-stress, and coupled thermal-electrical analysis in ABAQUS (see “Heat transfer analysis procedures: overview,” Section 6.5.1);
must appear in conjunction with a density definition (see “Density,” Section 16.2.1); and
always makes an analysis nonlinear.
Latent heat effects can be significant and must be included in many heat transfer problems involving phase change. When latent heat is given, it is assumed to be in addition to the specific heat effect (see “Uncoupled heat transfer analysis,” Section 2.11.1 of the ABAQUS Theory Manual, for details).
The latent heat is assumed to be released over a range of temperatures from a lower (solidus) temperature to an upper (liquidus) temperature. To model a pure material with a single phase change temperature, these limits can be made very close.
As many latent heats as are necessary can be defined to model several phase changes in the material. Latent heat can be combined with any other material behavior in ABAQUS, but it should not be included in the material definition unless necessary; it always makes the analysis nonlinear.
If the phase change occurs within a known temperature range, the solidus and liquidus temperatures can be given directly. The latent heat should be given per unit mass.
Input File Usage: | *LATENT HEAT |
ABAQUS/CAE Usage: | Property module: material editor: ThermalLatent Heat |
In some cases it may be necessary to include a kinetic theory for the phase change to model the effect accurately in ABAQUS/Standard; for example, the prediction of crystallization in a polymer casting process. In such cases you can model the process in considerable detail using solution-dependent state variables (“User subroutines: overview,” Section 13.2.1) and user subroutine HETVAL.
Input File Usage: | Use the following options: |
*HEAT GENERATION *DEPVAR |
ABAQUS/CAE Usage: | Property module: material editor:
ThermalHeat Generation |
Latent heat effects can be used in all diffusive heat transfer, coupled temperature-displacement, and coupled thermal-electrical elements in ABAQUS but cannot be used with convective heat transfer elements. Strong latent heat effects are best modeled with first-order or modified second-order elements, which use integration methods designed to provide accurate results for such cases.
See “Freezing of a square solid: the two-dimensional Stefan problem,” Section 1.6.2 of the ABAQUS Benchmarks Manual, for an example of a heat conduction problem involving latent heat.