A simple perfect gas monitored volume where the relative pressure is a function of
relative volume or a function of time.
In the PRES monitored volume, the relative pressure is defined as
Prel = pressure inside of
monitored volume - atmospheric pressure.
The relative pressure is defined using a function in one of two ways. By default, the
relative pressure is defined as a function of the relative volume
, or the pressure can be a function
of time
.