# 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.