In this paper, we study the flow field characteristics and heat transfer of a rotating cylinder with a spanwise disk attached and subjected to low-velocity crossflow with a disk-cylinder diameter ratio, D-d/D-c = 3.06. Reynolds Averaged Navier Stokes (RANS) simulations using the k-epsilon realizable turbulence model with enhanced wall treatment were performed for various crossflow and rotational velocities. We were particularly interested in the case of a rotating cylinder, with a spanwise disk attached, in an air stream with a crossflow Reynolds number, Re-U = 23,560, and rotational Reynolds numbers, Rep, ranging from 5500 to 109,800. Large-eddy simulations (LES) using the dynamic kinetic energy subgrid-scale model were performed for Re-Omega= 54,900 and 109,800. Heat transfer results from the RANS simulations were compared to results from previous studies. Flow statistics computed from the LES calculations were compared to results measured by particle image velocimetry experiments. Unsteady flow patterns and thermal behaviours are discussed with reference to the instantaneous LES results. (C) 2013 Elsevier Ltd. All rights reserved.