This study presents a series of work on the fluid dynamics and heat transfer of swirling decaying flows that was produced using a set of axial vanes in a concentric annular pipe. The review of heat transfer enhancements using passive methods and in particularly swirling flow is provided. The problem of interest is described in details alongside, the methods used to investigate the hydrodynamics of swirling decaying flows and its implications as a heat transfer enhancement method is presented. Lastly, verification and validation results for the numerical simulation are presented. (C) 2015 Elsevier Ltd. All rights reserved.