26.2.3 Specific heat
Products: Abaqus/Standard Abaqus/Explicit Abaqus/CFD Abaqus/CAE
References
Overview
A material's specific heat:
is required for transient “Uncoupled heat transfer analysis,” Section 6.5.2; transient “Fully coupled thermal-stress analysis,” Section 6.5.3; transient “Coupled thermal-electrical analysis,” Section 6.7.3; and “Adiabatic analysis,” Section 6.5.4;
must be defined for an Abaqus/CFD analysis when the energy equation is active (“Energy equation” in “Incompressible fluid dynamic analysis,” Section 6.6.2);
must appear in conjunction with a density definition (see “Density,” Section 21.2.1);
can be linear or nonlinear (by defining it as a function of temperature); and
can be specified as a function of temperature and/or field variables.
Defining specific heat
The specific heat of a substance is defined as the amount of heat required to increase the temperature of a unit mass by one degree. Mathematically, this physical statement can be expressed as:
is the infinitessimal heat added per unit mass and 
is the entropy per unit mass. Since heat transfer depends on the conditions encountered during the whole process (a path function), it is necessary to specify the conditions used in the process to unambiguously characterize the specific heat. Thus, a process where the heat is supplied keeping the volume constant defines the specific heat as:
is the internal energy per unit mass.Whereas, a process where the heat is supplied keeping the pressure constant defines the specific heat as:
is the enthalpy per unit mass. In general, the specific heats are functions of temperature. For solids and liquids, 
and 
are equivalent; thus, there is no need to distinguish between them. When possible, large changes in internal energy or enthalpy during a phase change should be modeled using “Latent heat,” Section 26.2.4, instead of specific heat.Defining constant-volume specific heat
The specific heat per unit mass is given as a function of temperature and field variables. By default, specific heat at constant volume is assumed.
| Input File Usage: | *SPECIFIC HEAT |
The following option can also be used in Abaqus/CFD: *SPECIFIC HEAT, TYPE=CONSTANT VOLUME |
| Abaqus/CAE Usage: | Property module: material editor: Thermal |
Defining constant-pressure specific heat
In Abaqus/CFD the constant-pressure specific heat is required when the energy equation is used for thermal-flow problems.
| Input File Usage: | *SPECIFIC HEAT, TYPE=CONSTANT PRESSURE |
| Abaqus/CAE Usage: | Property module: material editor: Thermal |
Elements
Specific heat effects can be defined for all heat transfer, coupled thermal-electrical-structural, coupled temperature-displacement, coupled thermal-electrical, and fluid elements in Abaqus. Specific heat can also be defined for stress/displacement elements for use in adiabatic stress analysis.
Specific heat must be defined for all transient thermal analyses even if the only elements in the model are user-defined elements (“User-defined elements,” Section 32.17.1), in which case a dummy specific heat must be specified.