Computational Fluid Dynamics (CFD) Modeling of Interfacial Momentum Transfer in Bubbly Two-Phase Flow

Abstract

This dissertation addresses critical gaps in Computational Fluid Dynamics (CFD) modeling of momentum transfer in two-phase flow systems. Available models, based on empirical relations from the behavior of single bubbles in the Stokes regime, fail to capture the complex dynamics of bubbly flows involving multiple interacting bubbles. This research develops more accurate models by considering factors such as void fraction, shear, wake effects, and turbulence.

The study begins with a literature review that highlights discrepancies between standard modeling practices and the complexities of two-phase dynamics. It continues with CFD simulations employing preferred closure models for drag, lift, and other forces, benchmarked against experimental data to evaluate their accuracy and limitations. Insights from these comparisons inform a design exploration procedure that defines functional forms for drag and lift coefficient models with undetermined constants. An automated optimization process minimizes discrepancies between CFD analysis and experimental observations across various cases.

The dissertation concludes by comparing available models with the newly developed ones, demonstrating the latter's performance in predicting two-phase flow dynamics. This research contributes a methodologically robust and theoretically sound framework for advancing CFD modeling, impacting both academic research and industrial applications.