Understanding the Impact of Particle Morphology on Resuspension with a 3D Printed Wind Tunnel

EDWARD NEAL, Jonathan P. Reid, Richard J. Thomas, Maurice Walker, Jack Vincent, Simon Parker, Virginia Foot, Benjamin Higgins, University of Bristol

     Abstract Number: 201
     Working Group: Aerosol Physics

Abstract
Particle resuspension is omnipresent in our lives with activities such as cleaning, walking, and driving, all contributing to resuspended aerosol concentrations. Existing mechanistic models for resuspension, however, have limited complexity due to a lack of understanding on contributing factors and are neglected in aerosol dispersion models. This project aims to show that a low cost, small-scale, 3D printed wind tunnel offers an accessible route to filling this gap in experimental resuspension research.

The wind tunnel has been tailored to a laboratory setting with an open design that measures below one meter in length and a largest cross section of 256 cm2. It has been constructed to reflect the commonly studied resuspension scenario of a particle residing in the sub-viscous boundary layer of a fully developed turbulent flow. Dry compressed air enters the tunnel via a mass flow controller and is conditioned within a settling chamber before turbulence is induced and allowed to develop. Particle removal downstream is captured by a camera operating at 200-500 FPS. This high temporal resolution and data acquisition rate provides rarely recorded particle resuspension velocities and an insight into collision events that lead to multiple particles resuspending.

Within this research the potential limitations of using a 3D-printed approach are analysed with investigations into the effects of static and tunnel surface roughness on the resuspension of glass standards. This, alongside verification of the expected turbulent flow, provides validation of the ideal removal scenario and a foundation for introducing complexity to resuspension models.

Particles with varying, yet reproducible, morphologies can be manufactured with unique instruments at the University of Bristol where droplets are dried under controlled relative humidity conditions. When resuspended these particles will provide insight into how morphology impacts particle detachment and demonstrate the table-top wind tunnel as a method for rapid and accessible resuspension experiments.