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Commit e4128a10 authored by Matthieu Schaller's avatar Matthieu Schaller
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Better description of the EoS in the online documentation, especially of the isothermal case

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...@@ -7,18 +7,24 @@ ...@@ -7,18 +7,24 @@
Equations of State Equations of State
================== ==================
Currently (if the documentation was well updated), we have two different gas Currently, SWIFT offers two different gas equations of state (EoS)
equations of state (EoS) implemented: ideal and isothermal; as well as a variety implemented: ``ideal`` and ``isothermal``; as well as a variety of EoS for
of EoS for "planetary" materials. "planetary" materials. The EoS describe the relations between our
The EoS describe the relations between our main thermodynamical variables: main thermodynamical variables: the internal energy per unit mass
the internal energy (\\(u\\)), the density (\\(\\rho\\)), the entropy (\\(A\\)) (\\(u\\)), the mass density (\\(\\rho\\)), the entropy (\\(A\\)) and
and the pressure (\\(P\\)). the pressure (\\(P\\)).
Gas EoS Gas EoS
------- -------
In the following section, the variables not yet defined are: \\(\\gamma\\) for We write the adiabatic index as \\(\\gamma \\) and \\( c_s \\) denotes
the adiabatic index and \\( c_s \\) for the speed of sound. 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 .. csv-table:: Ideal Gas
:header: "Variable", "A", "u", "P" :header: "Variable", "A", "u", "P"
...@@ -38,7 +44,9 @@ the adiabatic index and \\( c_s \\) for the speed of sound. ...@@ -38,7 +44,9 @@ the adiabatic index and \\( c_s \\) for the speed of sound.
"P", "", "\\(\\left( \\gamma - 1\\right) u \\rho \\)", "" "P", "", "\\(\\left( \\gamma - 1\\right) u \\rho \\)", ""
"\\( c_s\\)", "", "\\(\\sqrt{ u \\gamma \\left( \\gamma - 1 \\right) } \\)", "" "\\( 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 Planetary EoS
------------- -------------
......
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