This book presents the Generalized Differential Quadrature and Chebyshev-Gauss-Lobatto Spectral Methods on the generalized Buongiorno's mathematical nanofluid model with the simplified Maxwell's equations and the Oberbeck-Boussinesq approximation. The significance of an externally applied magnetic field and an imposed negative temperature gradient on the onset of natural convection in a thin horizontal layer of alumina-water nanofluids for various sizes of spherical alumina nanoparticles and volumetric fractions are explored numerically in this book. Based on the linear stability theory, the stability equations are firstly derived formally using the normal mode analysis technique and secondly converted to a generalized eigenvalue problem considering more realistic boundary conditions. This book also highlights the thermo-magneto-hydrodynamic stability of the nanofluidic system and the critical size of convection cells in terms of the critical thermal Rayleigh number and the critical wave number, respectively. This book is ideal for researchers who are entering into Computational Fluid Dynamics.