- Instabilities on the flow structure are studied numerically on a channel formed by three-dimensional sinusoidal plates. Two geometrical configurations are analyzed formed by a phase angle of 0° and 180° between bottom and top plates. Results are reported for different Reynolds numbers and its influence on the heat transfer behavior. Results show that the instabilities on the flow structure generate a set of rolling vortex. These vortexes tend to generate a more uniform mixing which reduces the nonuniformities in the flow and a more efficient heat transfer. These arrangements also exhibit an increase in pressure drop to that of conventional flat plates. © 2009 by ABCM.