Sensing Dense Particulate Materials

Lead Research Organisation: University of Sheffield
Department Name: Mechanical Engineering

Abstract

Thousands of years ago, early Mesopotamian people discovered that a mixture of mud and straw creates strong durable buildings, what we call today a composite material. Composites are far better than the sum of their parts, for example they can be stronger and cheaper. Similar experiments with mixing fluids and gases led to the discovery of complex fluids. Composites, complex fluids, and powders can all be examples of particulate materials. These materials led to advances in food science and healthcare (emulsions, colloids, powders); automobile, aerospace, and construction (composites, cement), among many others.

Although these materials are highly valuable, we do not have accurate and simple ways to measure their structure. This is due to their complex microstructure, which is a random mix of different types of particles. However, measuring is the first step to automation and perfecting any product.

When using a powder for a chemical reaction, or producing an emulsion, the particles will constantly change size and properties. To automate these processes, we need to monitor the particle properties. In many cases the particle properties are simply unknown. For example, the pores (which are a type of particle) in bones. Measuring these pores would help diagnose and treat osteoporosis.

The end goal is to develop new sensing methods for dense particulates using ultrasound. To achieve this the first step is to understand how a sound wave reflects from these materials? To develop new sensing methods requires a team with engineers and mathematicians working together to develop: the maths of sound waves, consider how these sensors will be installed in industry, and use machine learning to deal with the complex microstructure of particulate materials.

Publications

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García Neefjes E (2022) A unified framework for linear thermo-visco-elastic wave propagation including the effects of stress-relaxation in Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences

 
Description Determination of particle attributes via novel active acoustics
Amount £124,186 (GBP)
Organisation Johnson Matthey 
Sector Private
Country United Kingdom
Start 10/2021 
End 10/2025
 
Title EffectiveWaves.jl 
Description A Julia package for calculating, processing and plotting waves travelling in heterogeneous materials. The focus is on ensemble averaged waves. At present, the package focuses on materails filled with randomly placed particles. You can calculate effective wavenumbers for 2D [1] and 3D [4] acoustics, wave transimission and wave reflection in 2D [1,2,3] and 3D [4], and scattering from an inhomogenious sphere [4]. See these notes for brief formulas on effective wavenumbers. Together with MultipleScattering.jl, this package has been setup to easily extend to other dimensions, materials, and types of waves, such as elastic and electromagnetic waves. 
Type Of Technology Software 
Year Produced 2022 
Open Source License? Yes  
Impact This software reproduces the state of the art in wave scattering from particulates. It allows others to access the results of the research without having to understand all the technical details. 
URL https://github.com/JuliaWaveScattering/EffectiveWaves.jl
 
Title MultipleScattering.jl 
Description A Julia library for simulating, processing, and plotting multiple scattering of waves. The library focuses on multipole methods (addition translation theorems) to solve the inhomogeneous Helmholtz equation (time-harmonic waves). Multipole methods are particularly efficient at solving scattering from particles in an infinite domain. This library is configured to use T-matrices (also known as scattering matrices) to represent scattering from particles with any shape and properties (currently implemented for acoustics). 
Type Of Technology Software 
Year Produced 2022 
Open Source License? Yes  
Impact The most used package for wave scattering in the language Julia. Currently 36 stars on Github 
URL https://github.com/JuliaWaveScattering/MultipleScattering.jl
 
Description International workshop at the Isaac Newton Institute 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact A week long workshop at the Isaac Newton Institute.

Waves propagating in complex and random media are key to many areas of physics and engineering. These media include gases, emulsions, powders, porous and polycrystalline materials, to name just a few. The theoretical tools to understand wave phenomena can be applied to all linear waves, such as elastic and electromagnetic. Yet, the community and the tools used are quite disconnected. This workshop aims to bridge the gaps between us, better understand our connections, and share recent advances.

Specific themes include:

Theoretical models of wave propagation, scattering and transport:
multiple scattering by particulates,
diagrammatic approaches,
strong fluctuation theory,
stochastic differential equations,
random matrix theory,
etc.
Numerical modelling of waves in complex media,
Near-field and mesoscopic wave phenomena,
Impact of structural correlations,
Design and inverse design of complex media to control wave properties,
Applications of waves in complex and random media.
Year(s) Of Engagement Activity 2023
URL https://www.newton.ac.uk/event/mwsw02/