A two-fluid model for violent aerated flows

In the study of ocean wave impact on structures, one often uses Froude scaling since the dominant force is gravity. However the presence of trapped or entrained air in the water can significantly modify wave impacts. When air is entrained in water in the form of small bubbles, the acoustic properties in the water change dramatically. While some work has been done to study small-amplitude disturbances in such mixtures, little work has been done on large disturbances in air-water mixtures. We propose a basic two-fluid model in which both fluids share the same velocities and analyze some of its properties. It is shown that this model can successfully mimic water-wave impacts on coastal structures. The governing equations are discretized by a second-order finite-volume method. Numerical results are presented for two examples: the dam break problem and the drop test problem. The results suggest that this basic model can be used to study violent aerated flows, especially by providing fast qualitative estimates. (C) 2009 Elsevier Ltd. All rights reserved.