Note on minmax principle for heat convection equation (Q1118495)

\textit{E. K. Barret}, \textit{G. Demunshi} and \textit{D. N. Shields} [Numerical analysis of singular perturbation problems, Proc. Conf. Nijmegen 1978, 401-408 (1979; Zbl 0411.76020)] have given a minmax principle for a non- self adjoint system and applied it to Navier-Stokes equations. Here, we give a minmax principle for the heat convection equation with viscous dissipation when the surface temperature is prescribed. For simplicity, we mention the situations where we may obtain the saddle functional.