# Simultaneous Eulerian-Lagrangian velocity measurements of particulate pipe flow in transitional regime

## TL;DR

This paper introduces a novel experimental setup and measurement technique for studying dilute particulate pipe flows during the transition to turbulence, enabling simultaneous velocity measurements of particles and fluid.

## Contribution

It presents a unique pipe flow rig with a combined 2D PIV/PTV technique that allows for phase discrimination and simultaneous velocity measurements in transitional particulate flows.

## Key findings

- Rig and technique effectively study transitional particulate flows.
- Phase discrimination separates particle and fluid images.
- Method enables detailed flow analysis in dilute regimes.

## Abstract

We present a unique pipe flow rig capable where simultaneous particle tracking and flow velocity measurements in a dilute, neutrally buoyant particulate pipe flow in regimes of transition to turbulence. The flow consists of solid glass spheres for the disperse phase, and a density-matching fluid for the carrier phase. The measurements are conducted using a bespoke, combined 2D PIV/ PTV technique. The technique takes advantage of a phase discrimination approach that involves separating the disperse and carrier phases based on their respective image characteristics. Our results show that the rig and the technique it implements can be employed to study transitional particulate pipe flows at dilute concentration.