In this book, effect of adding nanoparticles in to the base fluid on flow and heat transfer characteristic is examined. Several semi analytical methods are utilized to solve the governing equations. The fluids containing the solid nanometer size particle dispersion are called 'nanofluids'. Most of engineering problems, especially some heat transfer equations are nonlinear, therefore some of them are solved using numerical solution and some are solved using the different analytic method such as Homotopy Perturbation Method (HPM), Galerkin Optimal Homotopy Asymptotic Method (GOHAM), Differential Transformation Method (DTM), Adomian decomposition method (ADM, Homotopy Analysis Method (HAM).