Two fvModels have been added, densityConstraintSource and
pressureConstraintSource, for constraining the density or pressure of
zero-dimensional cases. The constrained property's variation in time is
specified by means of a Function1.
The constraints are maintained by adding or removing an appropriate
amount of mass. Properties are added or removed with this mass at their
current values. Both constraints therefore represent uniform expansion
or contraction in an infinite space. In the case of the pressure
constraint, the compressibility is used to determine this amount of
mass, and in the case of non-linear equations of state iteration may be
necessary to enforce the constraint accurately.
These models can be used to extend the concept of a zero-dimensional
simulation to one that uniformly expands or contracts, or features a
mass source or sink.
Example specification of a time-varying density constraint, in
constant/fvModels:
densityConstraintSource1
{
type densityConstraintSource;
rho
{
type scale;
values
(
(0 1.16)
(1 1.16)
(1.1 2.02)
(10 2.02)
);
}
}
Example specification of a constant pressure constraint:
pressureConstraintSource1
{
type pressureConstraintSource;
p 1e5;
}
An example in which the pressure is constrained is provided. This
example shows the reaction of nc7h16, and duplicates the behaviour of
the corresponding chemFoam case.
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