Unit System and Conventions

Naming Conventions

Parameter	Read As
p_bar	\(p\) \([bar]\)
alpha_w_per_m2k	\(\alpha\) \([\frac{W}{m^2 \cdot K}]\)
vdot_m3_per_s	\(\dot{V}\) \([\frac{m^3}{s}]\)

Reference State Values

For calculations of compressible media, the normal conditions following DIN 1343 are used:

Parameter	Value
NORMAL_PRESSURE	1.01325 \([bar]\)
NORMAL_TEMPERATURE	273.15 \([K]\)

Implemented Constants

Implemented physical constants can be found in the python module “constants.py”:

Constant	Value	Meaning
GRAVITATION_CONSTANT	9.81 \([\frac{m}{s^2}]\)	Gravitation constant
MOLAR_MASS_AIR	0.02896 \([\frac{m^3}{mol}]\)	Molar mass of air
R_UNIVERSAL	8.314 \([\frac{J}{K \cdot mol}]\)	Universal gas constant

Flow Directions

Edges between junctions are created using functions, which require a “from_junction” and a “to_junction” parameter, so the edges in the network are directed. A positive velocity value calculated for an edge is assumed to be positive if the flow direction is in alignment with the direction of the edge. Otherwise, the velocity value is negative.