Numerical investigations are carried out to determine the effect of change in geometrical parameter of annular fin on thermal and hydraulic characteristics. Fin shape is changed by varying horizontal diameter of fin. Three different cases of annular fin are investigated corresponding to fin diameter ratio (X) of 0.65, 0.85 and 1. Turbulence is modelled using k-ω shear stress transport model. Relative assessment of tube with annular fin of different horizontal diameter (D01) is done for 2500 <

more »

... < 13000. The comparison of Nusselt number reveals that circular tube with annular fin enhances heat transfer rate. Nusselt number augments by 35% and 10% in case of annular fin with diameter ratio of 0.65 and 0.85 as compared to that of annular fin with diameter ratio of 1.00 for 2500 < Re< 13000. Pressure drop augments with increase in horizontal diameter of fin and Reynolds number. Annular fin with diameter ratio of 0.65 performs better in terms of heat transfer and pressure penalty as compared to other cases for range of reported Reynolds number.