Thermal diffusivity definitions

Thermal diffusivity

thermal diffusivity is the ratio of the time derivative of temperature to its curvature, quantifying the rate at which temperature concavity is `smoothed out`. In a sense, thermal diffusivity is the measure of thermal inertia. In a substance with high thermal diffusivity, heat moves rapidly through it because the substance conducts heat quickly .....
Found on http://en.wikipedia.org/wiki/Thermal_diffusivity

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thermal diffusivity

the ratio of the thermal conductivity to the volumetric heat capacity .
Found on https://nsidc.org/cryosphere/glossary?page=26

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Thermal Diffusivity

The ratio of heat conducted to the heat stored per unit volume.whereD = thermal diffusivity [m²s^-1]k = thermal conductivity [Wm^-1K^-1]? = density [kgm^-3]C_p = specific heat at constant pressure [Jkg^-1K^-1]
Found on https://www.encyclo.co.uk/local/20687

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