Numerical simulations performed on wavy walled microchannels confirm the presence of chaotic advection in them. A chaotic advection regime enhances mixing and as a consequence heat transfer. Investigating the steady flow regime in converging-diverging microchannels, it is observed that channels with highly modulated walls may culminate in strong chaotic advection which results in significant heat transfer enhancement albeit with a considerable pressure drop. On the other hand, by introducing a pulsatile flow, strong chaotic advection may be achieved at relatively smaller Reynolds numbers for channels with slightly modulated walls and with a reasonable pressure drop penalty. The effects of pulsation frequency and amplitude are investigated and it is observed that there is a characteristic frequency at which heat transfer is maximized. For the cases investigated, this nominal frequency is approximately 40 Hz. The characteristic frequency is shown to be a function of geometry and flow parameters. High heat transfer augmentations and moderate pressure drop penalties are observed using this technique which incorporates pulsatile flow. (C) 2014 Elsevier Ltd. All rights reserved.