This document presents a CFD study of heat transfer from a circular cylinder confined between two parallel plates. The study uses ANSYS Fluent to model flow at Reynolds numbers from 0.038 to 10,000. It finds that heat transfer, as measured by Nusselt number, increases with Reynolds number due to stronger convection. Flow patterns transition from steady to vortex shedding as Reynolds number increases. The results agree with previous experiments and provide insights into how Reynolds number and thermal boundary conditions affect the temperature field and heat transfer rate from the cylinder.