A generalised Lagrangian formalism for thermal analysis of laminar convective heat transfer

► Generalization Lagrangian heat-transfer formalism to non-uniform reference states. ► Clear definition and physical interpretation of convective flux and thermal paths. ► Resolution fundamental ambiguity of the reference state of existing formalisms. ► Formulation comprehensive geometrical framework for composition of thermal paths. ► Illustrative Lagrangian thermal analysis using concepts from mixing studies.