NUMERICAL STUDY OF DEVELOPING NATURAL LAMINAR CONVECTION IN A VERTICAL HYPERBOLIC DUCT OF A FIXED LENGTH AND WITH A CONSTANT WALL TEMPERATURE

Abstract

The natural laminar convection in a vertical hyperbolic duct of a fixed length and with a constant wall temperature is numerically investigated. The governing equations are solved by a finite difference method. The results are obtained for the velocity, temperature, and pressure fields, and for the mean heat transfer coefficient. The numerical calculations are fulfilled for Rayleigh numbers ( Ra ) ranging from 5 to 3 · 104 and for the numerical eccentricity ranging from 5 to 100. The effects of the numerical eccentricity and Ra are examined and the results are compared with those of a cylindrical vertical duct. It was found that the flow fields and Nusselt number ( Nu ) are affected significantly at small values of the numerical eccentricity and Ra .