Numerical simulation of natural convection in a vertical annulus with a localized heat source

The present numerical investigation deals with the size and location effects of a single isoflux discrete heater on the buoyancy induced convection in a cylindrical annulus. A discrete heater is placed at the inner wall, while the top and bottom walls as well as the unheated portions of the inner wall are kept adiabatic, and the outer wall is maintained at a lower temperature. The influence of location and size of the discrete heater on the convective flow and the corresponding heat transfer are obtained for a wide range of physical parameters. The predicted numerical results reveal that the placement of heater near the middle portion of inner wall yields a maximum heat transfer and minimum hot spots rather than placing the heater near the top and bottom portions of the inner wall. We found that the location of heater affects the rates of flow circulation and heat transfer in a complex fashion. The rate of heat transfer is an increasing function of radii ratio of the annulus. Further, we found that the rate of heat transfer and maximum temperature in the annular cavity are significantly modified by the heater length and location.