The flow and forced convection heat transfer from one and two rotating circular cylinders in side by side arrangement is investigated numerically with an Over set grid method. In the case of one rotating cylinder, numerical simulations are performed at Reynolds numbers, Re , 100-1000 and non dimensional rotation rates, ?, varying from 0 to 6. The Prandtle number is taken to be 0.7 and 7. As ? increase, the flow and thermal field become stabilized and finally the vortex shedding completely suppresses beyond the critical rotation rate, ? I , that shows an increasing trend with Reynolds number. Further increase in rotation rates result in a second unsteady pattern beyond a critical rotation rate, ? II and the vortex shedding suppression is observed again beyond a third critical rotation rate, ? III and eventually, the flow and thermal field become steady. The second and third critical rotation rates show a decreasing pattern with Reynolds number. As ? increase, drag and lift coefficients decrease and increase respectively in all Reynolds numbers. The behavior of the time averaged Nusselt number shows a decreasing pattern with increasing rotation rate and increasing pattern with increasing Re and Pr numbers. In the case of two inward rotating cylinders, numerical simulations are performed at Reynolds numbers, Re , of 100, 200 and 500 and non dimensional rotation rates, ? , varying from 0 to 2. The spacing ratios, T/D , are 1.2, 1.8, 2.5 and 4 and the Prandtl number, Pr , has been taken to be 0.7 and 7. As ? increase, the flow and thermal field become stabilized and finally steady beyond the critical rotational speed, ? s , depending on the spacing ratio and Reynolds number. The value of ? s shows an increasing trend with increasing T/D for a fixed Reynolds number. For a fixed spacing ratio, as Re increases, the critical rotational speed increases. Regardless of the spacing ratio, drag and lift coefficients show a decreasing and increasing trend with increasing ? , respectively. The value of these coefficients shows no significant changes for different Reynolds numbers. As ? increases, Heat transfer from cylinders decreases for all the values of T/D and Re . The behavior of the time and surface averaged Nusselt number has the increasing pattern with increasing Reynolds and Prandtl number. In the case of two outward rotating cylinders, numerical simulations are performed at Reynolds numbers, Re , of 100 and non dimensional rotation rates, ? , varying from 0 to 5. The spacing ratios, T/D , are 1.8, 2.5 and 4 and the Prandtl number, Pr , has been taken to be 0.7 and 7. As ? increase, the flow and thermal field become stabilized and finally steady beyond the critical rotational speed, ? s , depending on the spacing ratio and Reynolds number. The value of ? s shows an decreasing trend with increasing T/D . Regardless of the spacing ratio, drag and lift coefficients show a decreasing and increasing trend with increasing ? , respectively. As ? increases, Heat transfer from cylinders decreases for all the values of T/D . The behavior of the time and surface averaged Nusselt number has the increasing pattern with increasing Prandtl number. Key Words : Rotating cylinders, Cross flow, Overset grid Method, Drag and lift coefficients, Vortex shedding suppression, Nusselt and Strouhal numbers.