# Visualization of Feature Separation in Advected Scalar Fields

## TL;DR

This paper introduces a novel spatio-temporal visualization method for feature separation in fluid flows, using particle tracking and segmentation to better understand the evolution of scalar features over time.

## Contribution

The paper presents a new visualization technique that segments feature volumes based on their contribution to separated features, improving analysis of topological changes in fluid flows.

## Key findings

- Effective visualization of feature separation in multiphase flows
- Application to liquid-gas and liquid-liquid flows demonstrates utility
- Enhanced understanding of scalar feature evolution over time

## Abstract

Scalar features in time-dependent fluid flow are traditionally visualized using 3D representation, and their topology changes over time are often conveyed with abstract graphs. Using such techniques, however, the structural details of feature separation and the temporal evolution of features undergoing topological changes are difficult to analyze. In this paper, we propose a novel approach for the spatio-temporal visualization of feature separation that segments feature volumes into regions with respect to their contribution to distinct features after separation. To this end, we employ particle-based feature tracking to find volumetric correspondences between features at two different instants of time. We visualize this segmentation by constructing mesh boundaries around each volume segment of a feature at the initial time that correspond to the separated features at the later time. To convey temporal evolution of the partitioning within the investigated time interval, we complement our approach with spatio-temporal separation surfaces. For the application of our approach to multiphase flow, we additionally present a feature-based corrector method to ensure phase-consistent particle trajectories. The utility of our technique is demonstrated by application to two-phase (liquid-gas) and multi-component (liquid-liquid) flows where the scalar field represents the fraction of one of the phases.