This paper presents a particle-based visualization approach for finite-time analysis of the connectivity of fluid portions in multiphase flow, i.e., the evolution of the droplets in volume of fluid simulations. We address the Lagrangian inconsistency between the interpolated flow field and the interpolated volume of fluid field by a correction approach, and complement that with an uncertainty measure that provides an estimate of the involved inconsistency. We demonstrate the utility and versatility of our approach using different multiphase flow simulations, exemplify its application in physics-based assessment of droplet formation processes, and discuss its limitations and benefits.

In single-phase flow visualization, research focuses on the analysis of vector field properties. In two-phase flow, in contrast, analysis of the phase components is typically of major interest. So far, visualization research of two-phase flow concentrated on proper interface reconstruction and the analysis thereof. In this paper, we present a novel visualization technique that enables the investigation of complex two-phase flow phenomena with respect to the physics of breakup and coalescence of inclusions. On the one hand, we adapt dimensionless quantities for a localized analysis of phase instability and breakup, and provide detailed inspection of breakup dynamics with emphasis on oscillation and its interplay with rotational motion. On the other hand, we present a parametric tightly linked space-time visualization approach for an effective interactive representation of the overall dynamics. We demonstrate the utility of our approach using several two-phase CFD datasets.

Piecewise linear interface calculation (PLIC) is one of the most widely employed reconstruction schemes for the simulation of multiphase flow. In this visualization paper we focus on the reconstruction from the simulation point of view, i.e., we present a framework for the analysis of this reconstruction scheme together with its implications on the overall simulation. By interpreting PLIC reconstruction as an isosurface extraction problem from the first-order Taylor approximation of the underlying volume of fluid field, we obtain a framework for error analysis and geometric representation of the reconstruction including the fluxes involved in the simulation. At the same time this generalizes PLIC to higher-order approximation. We exemplify the utility and versatility of our visualization approach on several multiphase CFD examples.