## Thermal diffusivity

Can the thermal diffusivity of an ideal gas be given by $\frac{\bar{\nu}^2}{3\gamma Z}$, where $\bar{\nu}$ is the root-mean-square speed of the particles, γ is the adiabatic index of the gas, and Z is the collision frequency?

The units check out, but I'm unsure of whether or not it works.
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