Interfacial phenomena and heat transfer associated with multi-droplet impact on flowing liquid film

This study addresses multiple droplets impact on a flowing liquid film numerically based on a three-dimensional model developed previously. Major contents include interfacial behavior and heat transfer associated with both successive and simultaneous impacts regarding the effect of film velocity. Shearing force induced by the flowing film breaks symmetry of both interface evolution and heat transfer. Increasing film velocity promotes upstream splashing but suppresses downstream splashing, while heat transfer coefficient is enhanced and shifted toward downstream collectively. Interface evolutions present three-dimensional feature, which makes the two-dimensional numerical scheme questionable. Comparing successive and simultaneous cases shows that the former is far more complicated than the latter. The interaction site prior to the impacting of trailing droplet in the successive case is highly dependent on the film velocity, resulting in a variety of complicated interfacial phenomena and nonuniform distributions of wall temperature and heat transfer coefficient.