This study experimentally and numerically investigated the effects of heater power and rotation speed of cylinders on the Nusselt number in a tank containing water. Two aluminum cylinders were placed horizontally at a certain height in the water tank with an isoflux heater inside each cylinder. Using the realizable k-ε turbulence model, the problem was numerically evaluated in 3D, steady-state, and incompressible conditions. Isotherms, streamlines, and Nusselt number variation around the cylinders were reported for each test case in the range of 1 < Ri < ∞, 3 × 108 < Ra < 7 × 108 and Re = 0, 1570, 3140, where Ri, Ra, and Re indicate Richardson, Rayleigh, and Reynolds numbers, respectively. The results showed that the rotation speed was the dominant factor. In addition, the Nusselt number increased by about 10% when the speed of rotation (ω) changed from half of the maximum to the maximum value. However, this increase was approximately 5% when the heater power (Q) changed. In the best scenario with Q = 1200 W and ω = 30 rpm, the Nusselt number was 108.1 by enhancing almost 19% heat transfer. Changes in average Nusselt number based on dimensionless parameters like Ra, Ri, and Re were observed, and the experimental data and correlations were compared.
