The integrated processes of flame acceleration, deflagration-to-detonation transition (DDT), and the resulting detonation propagation in micro- and macro-scale channels are simulated. It is found that the modes of flame acceleration and DDT in these two channels are different, being primarily controlled by viscosity and turbulent flame development, respectively. Furthermore, while boundary layer ignition is crucial for DDT in both channels, viscous wall friction is the key to self-sustained propagation in micro-channels, leading to momentum loss and consequently deficit of the detonation velocity. In macro channels, the strong overdriven detonation decays and gradually evolves into the Chapman-Jouguet detonation. (C) 2016 The Authors. Published by Elsevier Inc. on behalf of The Combustion Institute. This is an open access article under the CC BY-NC-ND license.