“…There is extensive literature on penetrative convection via an internal heat source, see, for example, Carr, 41 Capone et al, 42,43 Gangadharaiah et al, 44 Shivakumara and Dhananjaya, 45 Goluskin and van der Poel, 46 Mahajan and Nandal, 47 and Mahajan et al 48 Recently, Gangadharaiah et al 49 investigated the effect of the internal heat source of double‐diffusive convection where the fluid layer is overlying a porous layer using a linear instability analysis. Furthermore, Noon and Haddad 50 investigated the stability analysis of double‐diffusive convection when the reaction and internal heat source effects are present, in which the layer has been salted and heated from the bottom for the Darcy–Brinkman model in local thermal nonequilibrium (LTNE) porous material. There are three various functions of the internal heat sources that are taken into account: increasing through the layer, decreasing through the layer, and the layer being heated and cooled irregularly.…”