# Thermal Diffusivity

Written by Jerry Ratzlaff on . Posted in Thermodynamics

Thermal diffusivity, abbreviated as αD (Greek symbol alpha with a subscript D), is a measure of the transient thermal reaction of a material to a change in temperature. This is different than the the thermal diffusivity tensor which is abbreviated as α (Greek symbol alpha [note no subscript]).

### Thermal Diffusivity formula

$$\large{ \alpha_D = \frac {k_t} {p \; Q } }$$

Where:

$$\large{ \alpha_D }$$  (Greek symbol alpha) = thermal diffusity [m2/s or ft2/s]

$$\large{ p }$$ = density

$$\large{ Q }$$ = specific heat capacity

$$\large{ k }$$ = thermal conductivity

Solve for:

$$\large{ p = \frac {k} {\alpha \; Q} }$$

$$\large{ Q = \frac {k} {\alpha \; p} }$$

$$\large{ k = \alpha \; p \; Q }$$