Natural Convection Inside Vertical Isothermal Ducts of Constant Arbitrary Cross Section

摘要

A model for steady laminar natural convection inside vertical, arbitrarily shaped isothermal ducts of constant cross section is presented. The model is based on a combination of asymptotic solutions for fully developed and developing, boundary-layer flow. The fully developed asymptote model utilizes forced convection, internal flow modeling techniques, and an approximate model is presented, which is valid for a wide range of duct shapes and aspect ratios. The model is validated using experimental data and numerical results from the literature for a variety of duct shapes, including the triangle, square, circle, rectangle and the special case of parallel plates. The model is in good agreement with all of the data, with an rms percent difference of 10% or less in most cases.