2. Conduction

In solids or fluids at rest (gas, liquid with zero velocity or mass flow), heat transfer takes place by diffusion. This is also the case in the boundary layer of a fluid developed close to a wall, where diffusive transport predominates over advective transport. Thermal conduction is described by Fourier's law (2) . Thermal conductivityk (W · m ^–1 · K ^–1 ) depends on the material in which the conductive transfer takes place, and is a function of temperature. The vector notation of the relationship indicates that the phenomenon is three-dimensional. It is therefore possible to have a tensor defining the thermal conductivity of a...