Numerical simulations have been made on the flow and heat-and-mass transfer in a laminar liquid film falling down along a vertical wall by using a boundary-fitted coordinate system. The development of a two-dimensional wave was successfully predicted, which consists of a large solitary wave and ripple waves in front of it. In the large wave a circulating flow exists, and the heat and mass transfer is enhanced by the wave. Further, it was shown by a three-dimensional calculation that a two-dimensional wave becomes unstable with the increase of Re number, resulting in U-shaped three-dimensional wave. The mass transfer rate increases with the transition from two-dimensional to three-dimensional waves. The calculated mass transfer coefficient roughly agrees with empirical correlations.

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