Laminar periodically developed forced convection in sinusoidal corrugated-plate channels with uniform wall temperature, and single-phase constant property flows is considered. Numerical solutions are obtained using the control-volume finite-difference method for a wide range of channel corrugation aspect ratios (0 less than or equal to gamma less than or equal to 1), and flow rates (10 less than or equal to Re less than or equal to 1000) of viscous liquids (Pr = 5, 35, and 150). The flow field is found to be strongly influenced by gamma and Re, and it displays two distinct regimes: a low Re or gamma undisturbed laminar-flow regime, and a high Re or gamma swirl-flow regime. In the no-swirl regime, the flow behavior is very similar to that in fully developed straight-duct flows with no cross-stream disturbance. In the swirl regime, flow separation and reattachment in the corrugation troughs generates transverse vortex cells that grow spatially with Re and gamma, and the transition to this regime also depends on Re and gamma. The mixing produced by these self-sustained transverse vortices is found to significantly enhance the heat transfer, depending upon gamma, Re, and Pr, with a relatively small friction factor penalty. The consequent exchanger compactness and heat transfer enhancement effectiveness (j/f) is up to 5.5 times that for parallel-plate channels. (C) 2003 Elsevier Ltd. All rights reserved.