Thermal effusivity

In thermodynamics, the thermal effusivity or thermal responsivity of a material is defined as the square root of the product of the material's thermal conductivity and its volumetric heat capacity. In thermodynamics, the thermal effusivity or thermal responsivity of a material is defined as the square root of the product of the material's thermal conductivity and its volumetric heat capacity. Here, λ {displaystyle lambda } is the thermal conductivity, ρ {displaystyle ho } is the density and c p {displaystyle c_{p}} is the specific heat capacity. The product of ρ {displaystyle ho } and c p {displaystyle c_{p}} is known as the volumetric heat capacity. A material's thermal effusivity is a measure of its ability to exchange thermal energy with its surroundings. If two semi-infinite bodies initially at temperatures T 1 {displaystyle T_{1}} and T 2 {displaystyle T_{2}} are brought in perfect thermal contact, the temperature at the contact surface T m {displaystyle T_{m}} will be given by their relative effusivities.