Reply To: TWO TEMPERATURE MODEL PROBLEM WITH ANSYS FLUENT 21 R2

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Hello Oreste Russo,

The two temperature model is actually used to measure the degree of the non equillibrium temperature effect in hypersonic flows by the use of Damkohler number. 

The Damkohler number is defined as the ratio of flow time scale / reaction time scale. The flow time is affected by the fluid velocity which is related to the mach number and the reaction time is related to thermochemical properties where the temperature also plays a significant effect.

For the hypersonic flows, the Damkohler number is typical of the order of unity.

This indicates that the fluid element does not reside at one location long enough to bring the local thermodynamic state to equilibrium, and therefore the flow is in thermal non-equilibrium.

To properly address this effect, it is necessary to use a two-temperature model that assumes: the translational and rotational energy modes of species are in equilibrium with one temperature; and the vibrational and electronic energy modes of species are in equilibrium with another temperature.

 A system of conservation equations is solved that includes the Navier-Stokes equations and one additional transport equation that models the conservation of vibrational-electronic energy.

For further detailed information on the exact equations involved in the two temperature model kindly go through the attached user guide link which is shown below

5.2.3. The Two-Temperature Model for Hypersonic Flows (ansys.com)

I hope this solves your issue.

Thanks,