For inelastic non-Newtonian fluids, two alternatives are available. The first option is to specify the material using the non-Newtonian material property groups (see Fluid Flow Material Properties: Inelastic Non-Newtonian Material Model in the COMSOL Multiphysics Reference Manual). Alternatively, it is possible to use built-in functionality to account for temperature variations using predefined thermal functions (see Fluid Properties for more details). The later option is also available for viscoelastic fluids.