Laminar natural convection in enclosures having irregular geometries

Heat transfer by natural convection through fluid layers in complex geometries is of interest in many engineering applications such as cooling of electronic equipments, solar energy collectors and others. In this work numerical solutions are produced for heat transfer in steady-state laminar free convection in three different types of enclosures having different geometries.; In the first section, the steady-state laminar natural convection for air bounded by two confocal horizontal elliptical cylinders has been studied numerically for the case of inner hot and outer cold isothermal surfaces. The local and average Nusselt numbers are determined over the range of Rayleigh numbers from 10{dollar}sp4{dollar} to 2 {dollar}times{dollar} 10{dollar}sp5{dollar} for different eccentricities of the inner surface. Correlations are given for the average Nusselt number based on both the inner and the outer surfaces.; In the second section, the problem of laminar natural convection is solved for air bounded by a hot flat plate and a cold cylinder for the case of isothermal surfaces. A correlation is presented for the average Nusselt number over the range of Rayleigh number from 10{dollar}sp5{dollar} to 10{dollar}sp6{dollar} for different values of the width aspect ratio {dollar}Ssb{lcub}w{rcub}{dollar} and thickness aspect ratio {dollar}Ssb{lcub}t{rcub}{dollar}.; Finally, the steady-state laminar natural convection for air from arrays of semi-circular heat-generating modules in a rectangular enclosure is studied numerically. Effects of different types of boundary conditions, the number of heaters, the width-aspect ratio {dollar}Ssb{lcub}w{rcub}{dollar} and Rayleigh number on the local and average Nusselt number are examined. Two different types of boundary conditions used included (i) top and bottom cold and (ii) top and bottom insulated.