Defining the caloric gas model

Thermodynamic property calculations in the Combustion Toolbox depend on the caloric gas model used to describe the variation of specific heats and chemical effects. This behavior is controlled through the CaloricGasModel enumeration class, which provides the following options:

• Calorically perfect gas — perfect. Assumes constant specific heats.

• Thermally perfect gas — thermallyPerfect. Assumes temperature-dependent specific heats.

• Calorically imperfect gas — imperfect. Assumes temperature-dependent properties and chemical equilibrium (default).

Selecting a caloric gas model

A caloric gas model is defined by selecting one of the enumeration values:

caloricGasModel = CaloricGasModel.perfect;
caloricGasModel = CaloricGasModel.thermallyPerfect;
caloricGasModel = CaloricGasModel.imperfect;

Modifying caloric model

An existing caloric gas model can be modified using the provided setter methods:

caloricGasModel = caloricGasModel.setPerfect();
caloricGasModel = caloricGasModel.setThermallyPerfect();
caloricGasModel = caloricGasModel.setImperfect();

Using the caloric gas model in solvers

The caloric gas model is passed directly to solvers, such as the ShockSolver, using the caloricGasModel option.

solver = ShockSolver( 'problemType', 'SHOCK_I', 'caloricGasModel', CaloricGasModel.imperfect);

This allows the same physical problem to be solved using different thermodynamic assumptions.

Checking the caloric gas model

To check which caloric model is currently selected, use the is* methods provided by the {mat:class}~src.+combustiontoolbox.+core.@CaloricGasModel.CaloricGasModel enumeration:

isPerfect          = caloricGasModel.isPerfect();
isThermallyPerfect = caloricGasModel.isThermallyPerfect();
isImperfect        = caloricGasModel.isImperfect();

These methods return a logical value (true/false) and are useful for branching logic or reporting.

Legacy compatibility

For compatibility with legacy solver flags, the static method fromFlag() can be used:

caloricGasModel = CaloricGasModel.fromFlag(FLAG_TCHEM_FROZEN, FLAG_FROZEN);