  The generation of microbubbles upon the collision and interaction of liquid
bodies in a gaseous environment is a ubiquitous process in two-phase flows,
including large-scale phenomena like ship wakes, breaking waves and rain
showers. These collision and interaction events involve the relative approach
of pairs of liquid-gas interfaces. As these interfaces approach, the smallest
length scales of the system are dynamically reduced. This evolving disparity in
length scales is numerically challenging to resolve without the employment of
subgrid-scale (SGS) impact and breakup models. In this study, a physics-based
impact and breakup model for the generation of these microbubbles is developed
and implemented. The objectives of this study are to develop a computational
algorithm that identifies interface collision events that contribute to the
formation of microbubbles, to formulate a physics-based breakup model that
predicts the distribution of microbubble sizes using the characteristics of the
originating gas film, and to integrate these modules into a two-phase flow
solver that accurately captures the effects of bubbles of all sizes. In these
proceedings, an SGS model suitable for the aforementioned problems is proposed,
and the steps involved in implementing the proposed SGS model in a macroscale
flow solver are outlined. Two aspects of the development of this SGS model are
then discussed in detail. First, the formulation and implementation of the
first step of the SGS model, the collision detection algorithm, is detailed.
Second, preliminary findings of a numerical investigation intended to shed
light on breakup processes in turbulent two-phase flows are presented.
