Commit e4128a10 authored by Matthieu Schaller's avatar Matthieu Schaller
Browse files

Better description of the EoS in the online documentation, especially of the isothermal case

parent 691bb573
......@@ -7,18 +7,24 @@
Equations of State
==================
Currently (if the documentation was well updated), we have two different gas
equations of state (EoS) implemented: ideal and isothermal; as well as a variety
of EoS for "planetary" materials.
The EoS describe the relations between our main thermodynamical variables:
the internal energy (\\(u\\)), the density (\\(\\rho\\)), the entropy (\\(A\\))
and the pressure (\\(P\\)).
Currently, SWIFT offers two different gas equations of state (EoS)
implemented: ``ideal`` and ``isothermal``; as well as a variety of EoS for
"planetary" materials. The EoS describe the relations between our
main thermodynamical variables: the internal energy per unit mass
(\\(u\\)), the mass density (\\(\\rho\\)), the entropy (\\(A\\)) and
the pressure (\\(P\\)).
Gas EoS
-------
In the following section, the variables not yet defined are: \\(\\gamma\\) for
the adiabatic index and \\( c_s \\) for the speed of sound.
We write the adiabatic index as \\(\\gamma \\) and \\( c_s \\) denotes
the speed of sound. The adiabatic index can be changed at configure
time by choosing one of the allowed values of the option
``--with-adiabatic-index``. The default value is \\(\\gamma = 5/3 \\).
The tables below give the expression for the thermodynamic quantities
on each row entry as a function of the gas density and the
thermodynamical quantity given in the header of each column.
.. csv-table:: Ideal Gas
:header: "Variable", "A", "u", "P"
......@@ -38,7 +44,9 @@ the adiabatic index and \\( c_s \\) for the speed of sound.
"P", "", "\\(\\left( \\gamma - 1\\right) u \\rho \\)", ""
"\\( c_s\\)", "", "\\(\\sqrt{ u \\gamma \\left( \\gamma - 1 \\right) } \\)", ""
Note that when running with an isothermal equation of state, the value
of the internal energy written to the snapshots is meaningless. The
other quantities (pressure, entropy, ...) are, however, correct.
Planetary EoS
-------------
......
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