Introduction to the Method of Average Magnitude Analysis and Application to Natural Convection in Cavities

Abstract

The method of Average Magnitude Analysis is a mixture of the Integral Method and the Order of Magnitude Analysis. The paper shows how the differential equations of conservation for steady-state, laminar, boundary layer flows are converted to a system of algebraic equations, where the result is a sum of the order of magnitude of each term, multiplied by a weight coefficient. These coefficients are determined from integrals containing the assumed velocity and temperature profiles. The method is illustrated by applying it to the case of drag and heat transfer over an infinite flat plate. It is then applied to the case of natural convection over an infinite flat plate with and without the presence of a horizontal magnetic field, and subsequently to enclosures of aspect ratios of one or higher. The final correlation in this instance yields the Nusselt number as a function of the aspect ratio and the Rayleigh and Prandtl numbers. This correlation is tested against a wide range of small and large values of these parameters.