Cantera/Gases - Revision history

Admin: Fix math tag formatting: remove unnecessary newlines inside <math> tag for cleaner rendering (via update-page on MediaWiki MCP Server)

2026-06-14T23:16:03Z

Fix math tag formatting: remove unnecessary newlines inside <math> tag for cleaner rendering (via update-page on MediaWiki MCP Server)

← Older revision		Revision as of 23:16, 14 June 2026
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	One of the most important rules about phases is the Gibbs phase rule (http://en.wikipedia.org/wiki/Phase_rule). This rule states that the number of degrees of freedom that must be specified for a gas to have a fixed thermodynamic state is given by the formula:		One of the most important rules about phases is the Gibbs phase rule (http://en.wikipedia.org/wiki/Phase_rule). This rule states that the number of degrees of freedom that must be specified for a gas to have a fixed thermodynamic state is given by the formula:

	<math>		<math>F = C - P + 2</math>
	F = C - P + 2
	</math>

	where:		where:

2017-04-17T08:37:25Z

The Basics

← Older revision		Revision as of 08:37, 17 April 2017
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	These keywords can be used with the phase <code>set</code> method,		These keywords can be used with the phase <code>set</code> method,

	<~~source lang="python"~~>		<pre>
	from Cantera import *		from Cantera import *

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	g.set(X="H2:1.0, CO2:3.0", T=298.15, P=OneAtm)		g.set(X="H2:1.0, CO2:3.0", T=298.15, P=OneAtm)
	g.set(P=OneAtm, Rho=0.10)		g.set(P=OneAtm, Rho=0.10)
	</~~source~~>		</pre>

	==Specifying Composition==		==Specifying Composition==

2017-04-17T08:33:38Z

2014-03-27T02:18:39Z

@@ Line 3: / Line 3: @@
 =Theory=
-We can begin with the Gibbs phase rule, which relates the number of phases and components in a system to the number of degrees of freedom - the number of independent thermodynamic parameters that must be set to fix the state of a gas.
+One of the most important rules about phases is the Gibbs phase rule (http://en.wikipedia.org/wiki/Phase_rule). This rule states that the number of degrees of freedom that must be specified for a gas to have a fixed thermodynamic state is given by the formula:
 =Specifying Thermochemical State=

2014-03-27T02:17:56Z

← Older revision		Revision as of 02:17, 27 March 2014
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	Some scattered notes on Cantera gas objects.		Some scattered notes on Cantera gas objects.

			=Theory=

			We can begin with the Gibbs phase rule, which relates the number of phases and components in a system to the number of degrees of freedom - the number of independent thermodynamic parameters that must be set to fix the state of a gas.

			More info over at [[Cantera/Phases]]

	=Specifying Thermochemical State=		=Specifying Thermochemical State=

2014-01-22T22:50:50Z

Vector Specification

← Older revision		Revision as of 22:50, 22 January 2014
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	<pre>		<pre>
	~~In [24]: g.set(Y="H2:1.0, O2:8.0")~~

	~~In [25]: clear~~

	In [26]: iO2 = g.speciesIndex('O2')		In [26]: iO2 = g.speciesIndex('O2')

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	</pre>		</pre>

	Now set our mole fractions:		Now we can set our mole fractions:

	<pre>		<pre>
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	</pre>		</pre>

	Alternatively, set the mass fractions:		Alternatively, we can set the mass fractions:

	<pre>		<pre>

2014-01-22T22:50:15Z

Specifying Composition

← Older revision		Revision as of 22:50, 22 January 2014
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	Out[14]: ['H2', 'H', 'O', 'O2', 'OH', 'H2O', 'HO2', 'H2O2', 'AR']		Out[14]: ['H2', 'H', 'O', 'O2', 'OH', 'H2O', 'HO2', 'H2O2', 'AR']
	</pre>		</pre>

			===String Specification===

	We can specify composition with a string. Using mole fractions first:		We can specify composition with a string. Using mole fractions first:
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	In [16]: g.set(Y="H2:1.0, O2:8.0")		In [16]: g.set(Y="H2:1.0, O2:8.0")
	</pre>		</pre>

			===Vector Specification===

	Similarly, we can specify composition with a vector. First, we set up the problem by grabbing some information:		Similarly, we can specify composition with a vector. First, we set up the problem by grabbing some information:

2014-01-22T22:49:36Z

Specifying Composition

← Older revision		Revision as of 22:49, 22 January 2014
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	==Specifying Composition==		==Specifying Composition==

	Composition can be specified either as a string, or as an array.		Composition can be specified either as a string, or as an array. If a specified composition sums to greater than 1, the values for each species are normalized.

	Specifying composition as a string is the "human method": it ensures the user can specify which species have which quantities, in an arbitrary order.		Specifying composition as a string is the "human method": it ensures the user can specify which species have which quantities, in an arbitrary order.
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	<pre>		<pre>
	In [29]: molefracs = zeros(nsp,); molefracs[iO2] = 0.1; molefracs[iH2] = ~~0.9~~		In [29]: molefracs = zeros(nsp,); molefracs[iO2] = 1; molefracs[iH2] = 2

	In [30]: g.set(X=molefracs)		In [30]: g.set(X=molefracs)
			</pre>

			Alternatively, set the mass fractions:

			<pre>
			In [29]: massfracs = zeros(nsp,); massfracs[iO2] = 1.0; massfracs[iH2] = 8.0

			In [30]: g.set(X=massfracs)
	</pre>		</pre>

2014-01-22T22:47:42Z

Specifying Composition

← Older revision		Revision as of 22:47, 22 January 2014
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	</pre>		</pre>

	Similarly, we can specify composition with a vector. ~~Using mole fractions~~:		Similarly, we can specify composition with a vector. First, we set up the problem by grabbing some information:

	<pre>		<pre>
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	In [28]: nsp = g.nSpecies()		In [28]: nsp = g.nSpecies()
			</pre>

			Now set our mole fractions:

			<pre>
	In [29]: molefracs = zeros(nsp,); molefracs[iO2] = 0.1; molefracs[iH2] = 0.9		In [29]: molefracs = zeros(nsp,); molefracs[iO2] = 0.1; molefracs[iH2] = 0.9

2014-01-22T22:46:45Z

Specifying Composition

@@ Line 63: / Line 63: @@
 <pre>
 In [16]: g.set(Y="H2:1.0, O2:8.0")
 </pre>