This study aims to numerically investigate thermal-hydraulic performance augmentation of ellipsoidal 45o dimpled U-tubes with various bend curvatures, subjected to constant external heat flux (q″=10kW/m2), for a range of Reynolds numbers (5000 ≤ Re ≤ 30000). Three smooth U-bends with curvatures radii of 0.695Dh, 1.5Dh, and 2.0Dh, where Dh is hydraulic diameter of smooth tube, are used in both smooth and enhanced tubes. A comparison of thermal-hydraulic characteristics of dimpled and smooth U-tubes is carried out using steady-state Reynolds Averaged Navier Stokes simulations. The analysis shows that the performance of dimpled U-tube is superior to smooth tube for all bend curvatures. The swirl flow patterns generated by the dimples induce early flow reattachment in the post bend section of the tube which enhances its heat transfer rate. The dimpled U-tube having the shortest curvature radius significantly alters Dean vortices which leads to substantial improvement in its heat and flow performances. Contrary to smooth U-tube, the average thermo-hydraulic performance of the shortest radius of curvature of dimpled U-tube is enhanced by 21.4% while other curvature radii (1.5Dh, and 2.0Dh) dimple U-tubes enhances the performance by 10.7% and 8.9%, respectively.