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# Thermal Diffusivity

MichaelBartmess.Thermal Diffusivity

The **Thermal Diffusivity **calculator computes the thermal diffusivity (**α**) of a material based on the thermal conductivity (**κ**), density (**ρ**) and the material's specific heat capacity.(**c _{p}**).

**INSTRUCTIONS**: Choose units and enter the following:

- (
**k**) This is the thermal conductivity expressed as power (e.g. Watts) per (m•K) - (
**ρ**) This is the density of the material - (
**c**) This is the material's specific heat capacity expressed as energy (e.g. Joule) per (kg•K)_{p}

#### The Math / Science

The **Thermal diffusivity** of a material at a constant pressure is equal to the material's thermal conductivity divided by its density and its specific heat capacity. Thermal diffusivity is often used in Geosciences / Atmospheric Science. The formula for thermal diffusivity is:

where:

- α is the thermal diffusivity (m
^{2}/s) - k thermal conductivity (W /(m•K))
- ρ is the density (kg/m³)
- cp is the specific heat capacity (J/(kg•K))

**Note**: this calculator permits the user to adjust the units of power in the thermal conductivity factor. However, the power is converted to Watts and then placed in a ratio of Watts per meter-degrees Kelvin (W /(m•K)). In a similar vein, this calculator permits the user to adjust the units of energy in the specific heat capacity factor. However, the energy is converted to Joules and then placed in a ratio of Joules per kilogram-degrees Kelvin (J/(kg•K)).

**Thermal Diffusivity**, is used in 1 equation/constant.

**Equations and Constants **