Non-Fourier effects in macro- and micro-scale non-isothermal flow of liquids and gases. Review

Non-Fourier heat transfer is reviewed and examined for fluids possessing significant thermal relaxation and retardation times characterizing the response of the heat flux and the temperature gradient to changes in one another. Non-Fourier heat transport occurs in a wide range of applications, including superfluid helium, fluids subjected to rapid heating, and strongly confined fluids. For nanofluids both the relaxation and retardation times are expressed in terms of nanoparticle concentration and suspension properties. The parallels between non-Fourier fluids and viscoelastic polymeric solutions are established. For viscoelastic fluids, the constitutive equation for stress must be frame invariant, a condition that must also hold for the constitutive equation for heat flux. This survey examines a variety of conditions and flow configurations under which non-Fourier effects may be significant in the non-isothermal flow of both gases and liquids.