A polydisperse model for bubbly two-phase flow around surface ship

A three dimensional polydisperse model for bubbly two-phase flow around a s urface ship-is presented. The Boltzmann equation for the bubble mass probab ility density function is evaluated using a multigroup approach with groups of constant bubble mass. The intergroup transfer mechanisms are bubble bre akup, coalescence and the dissolution of air into the ocean, and their effe cts on the two-phase flow field are analyzed. A three dimensional two-fluid ; model is used for each bubble mass group to calculate the group's average gas velocity, resulting in four scalar equations per group. The air entrai nment process is modeled using simulated breaking bow waves and the steady- state evolution of the gas bubbles for zero Froude number is obtained. It w as found that intergroup transfer is very important in these flows. Some of the research areas that need further improvement for the numerical predict ion of polydisperse two-phase flow around a ship have been identified and a re discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.