The Thermal Diffusivity (`alpha`) represents the relationship between Thermal Conductivity (`kappa`) and the density of a fluid (`rho`) and the fluid's specific heat (`c_p`). The two terms, `rho c_p` together, is known to be the volumetric heat capacity. The Thermal Diffusivity is expressed in units of `m^2/sec`.
`alpha` = `kappa / (rho* c_p)`, where in an SI units example: