Comment on “energy Transfer Through Mixed Convection Within Square Enclosure Containing Micropolar Fluid with Non-Uniformly Heated Bottom Wall under the MHD Impact” [journal of Molecular Liquids, 249(2018) 831–842]

•A correct formulation of average Nusselt number for the case of sinusoidal heated wall is proposed.•Accurate dimensional analysis provides the correction of the mathematical model.•Comparison of the existing and the correct formulation is included.