Mixed Convection Boundary Layer Flow of a Nanofluid Past a Vertical Plate in a Doubly Stratified Porous Medium

This article deals with the study of thermal and mass stratification effects on mixed convection boundary layer flow over a semi-infinite vertical flat plate embedded in a porous medium saturated by a nanofluid. The effects of Brownian motion and thermophoresis are incorporated into the model for nanofluids. In addition, the thermal energy equations include regular diffusion and cross-diffusion terms. A suitable coordinate transformation is introduced, and the obtained system of nonsimilar, coupled and nonlinear partial differential equations is solved by implicit finite difference method. The effect of thermal and mass stratification parameters on the non-dimensional velocity, temperature, concentration and nanoparticle volume fraction are discussed. In addition, the heat and mass transfer rates at the plate are presented graphically for various values of stratification, Brownian motion, Thermophoresis, Darcy and mixed convection parameters including the modified Dufour number and Dufour-solutal Lewis number.