Unsteady Cylinder Flow in a Fin-Wall-Confined Domain: Vortex Shedding and Heat-Transfer Coupling - This talk presents a mechanistic analysis of unsteady laminar flow and heat transfer around a heated circular cylinder embedded in a simplified fin and tube heat exchanger segment. The study examines flow conditions before and after the Hopf bifurcation, where a steady wake evolves into a periodic vortex shedding regime. The main objective is to identify how coherent wake structures modify the thermal field and contribute to convective heat transfer enhancement in a confined three dimensional configuration. The analysis moves beyond global quantities such as drag, lift, outlet temperature, and mean Nusselt number. Proper orthogonal decomposition is used to extract dominant flow and temperature structures, while extended proper orthogonal decomposition evaluates how velocity modes are linked with thermal fluctuations. Transfer entropy is then applied as a complementary diagnostic to examine the directionality of information transfer between velocity components and temperature signals. Preliminary results suggest that the transverse motion of the wake may be more strongly associated with temperature fluctuations than the streamwise velocity deficit alone. The thermal response also shows a frequency locked character after the onset of periodic shedding, indicating repeated boundary layer renewal events. The proposed framework may later be extended to other confined heat transfer surfaces where vortex formation and wall proximity control convective performance.