NUMERICAL STUDY OF LAMINAR NATURAL CONVECTION IN A FINNED ANNULUS: LOW ISOTHERMAL BLOCKS POSITIONS

摘要

Natural convection in a finned concentric annulus filled with air is numerically simulated, using the centered finite difference method if the alternating direction implicit scheme is taken into account. Two isothermal blocks are attached to the inner cylinder and placed symmetrically in the low section of the annulus. The radius ratio, as well as the dimensionless width and height of the blocks, are kept constant. The effect of the Rayleigh number Ra varying between 1000 and 10,000 on the flow pattern and heat transfer rate is discussed. It is shown that unicellular and bicellular flows are observed, and the blocks increase the overall heat transfer rate for the studied range of Ra.