21. PHYSICAL_CONSTANTS Namelist

The value of physical constants used in Truchas physics models are set using this namelist. The default for all these constants is their value in SI units. When the input for a problem uses a different system of units, these may need to be assigned the corresponding value in that system of units.

Namelist Usage

Required/Optional:

Optional

Single/Multiple Instances:

Single

21.1. Namelist Variables

absolute_zero

The value of absolute zero temperature. This constant is used by thermal radiation boundary conditions and the enclosure radiation model.

Default:

\(0~\text{K}\)

Note:

Use \(-273.15\) for temperature in centigrade.

gas_constant

The universal gas constant. This constant is used by the evaporation heat flux model.

Default:

\(8.31446261815324~\text{J}/\text{mol}\cdot\text{K}\)

stefan_boltzmann

The Stefan-Boltzmann constant \(\sigma\). This constant is used by thermal radiation boundary condititions and the enclosure radiation model.

Default:

\(5.67\times10^{-8}~\text{W}/\text{m}^2\cdot\text{K}^4\)

vacuum_permeability

The magnetic permeability of free space. This constant is used by the electromagnetics solver.

Default:

\(4\pi\times10^{-7}~\text{N}/\text{A}^2\)

vacuum_permittivity

The electric permittivity of free space. This constant is used by the electromagnetics solver.

Default:

\(8.854188\times10^{-12}~\text{F}/\text{m}\)