.QCalc.Quantities .QCalc.QuantitiesThis package contains quantities (Real types) that
are instantiated to represent physical values (Real
variables). The unit attribute of each quantity is
used to denote the physical dimensionality in terms of fundamental
dimensions: angle (A), length (L), mass (M), amount of subtance
(N), and time (T).1 The
fundamental dimensions are combined according to the rules
established for unit strings [Modelica2010,
p. 210]. The abbreviations (A, L, M, N, T) are applied in
alphabetical order in each numerator and denominator. Temperature
and charge are considered derived dimensions as if the Faraday
constant (kF or 96485.3399 C/mol) and
the gas
constant (R or 8.314472 J/(mol K)) are
nondimensionalized. The quantity attribute of each
quantity is not used since it is redundant in this context. The
displayUnit attribute is only used for quantities that
imply a certain display unit. For example, Temperature is an
alias for Potential with a
default display unit of K. Some quantities have minimum values
(e.g., min=0 for PressureAbsolute).
This package (Quantities) is abbreviated as
Q throughout the rest of QCalc. Most quantities are named with
adjectives following the noun so that related quantities are
grouped when alphabetized.
Methods for unit checking have been established [Mattsson2008,
Broman2008,
Aronsson2009]
and can, in theory, be applied to dimension checking instead.
However, this does not work in Dymola as of 2014, so unit checking
must be turned off (Advanced.CheckUnits = false).
For more information, please see the documentation of the Units package.
1. This misnomer (unit attribute
for dimension) is necessary because Real variables do
not have a dimension attribute in Modelica. Beware
that:
unit="L" indicates a length quantity (not a
volume in litres).unit="T" indicates a time quantity (not a
magnetic flux in teslas).unit="A" indicates an angle (not a current
in amperes).unit="N" indicates an amount of substance
(not a force in newtons).Licensed by the Hawaii Natural Energy Institute under the
Modelica License 2
Copyright © 2009–2014, Hawaii
Natural Energy Institute and Georgia Tech Research
Corporation.
This Modelica package is free software and the use is completely at your own risk; it can be redistributed and/or modified under the terms of the Modelica License 2. For license conditions (including the disclaimer of warranty) see QCalc.UsersGuide.License or visit http://www.modelica.org/licenses/ModelicaLicense2.
