Define Thermal diffusivity law?
The concept of "thermal diffusivity" is a fundamental property that describes how heat is conducted through a material. It quantifies how quickly heat can diffuse or spread out within a substance relative to how much heat is actually conducted.
The thermal diffusivity law, also known as Fourier's law of heat conduction, mathematically relates the heat flux (Q) through a material to the temperature gradient (∇T) across the material. It can be expressed as:
Q = -k ∇T
Where:
- Q is the heat flux, which is the quantity of heat flowing through a unit area per unit time (measured in watts, for example).
- k is the thermal conductivity of the material, which indicates its ability to conduct heat (measured in watts per meter-kelvin).
- ∇T is the temperature gradient, which represents the change in temperature per unit length in a particular direction.
The negative sign in the equation indicates that heat flows from regions of higher temperature to regions of lower temperature.
To determine the heat flux (Q) or temperature gradient (∇T) according to the thermal diffusivity law, you would need to know the thermal conductivity (k) of the material and the specific conditions of the system in question.