
You may choose to define the following properties using kinetic theory when the ideal gas law is enabled:
If you are using kinetic theory for a fluid's viscosity (Equation 8.49), you will need to input the kinetic theory parameters and for that fluid. These parameters are the LennardJones parameters and are referred to by FLUENT as the "characteristic length'' and the "energy parameter'' respectively.
When kinetic theory is applied to calculation of a fluid's thermal conductivity only, no inputs are required.
If you are going to calculate a fluid's specific heat using kinetic theory (Equation 8.75), you will need to input the degrees of freedom for the fluid material.
If you use kinetic theory to define a mixture material's mass diffusivity (Equation 8.916), you will need to input and for each chemical species .
Inputs for Kinetic Theory
The procedure for using kinetic theory is as follows:
The parameters to be set are as follows:
See the beginning of this section to find out which parameters are required to calculate each property using kinetic theory.
Characteristic length is defined in units of Angstroms. The energy parameter is defined in units of absolute temperature. Degrees of freedom is a dimensionless input. All kinetic theory parameters are set to zero by default. Appropriate values for different materials can be found in the literature (e.g., [ 144]).