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Spatiotemporal Instabilities in Discontinuous Shear Thickening Fluids / PETER ANGERMAN

Swansea University Author: PETER ANGERMAN

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DOI (Published version): 10.23889/SUThesis.71080

Abstract

The aim of this work is to study instabilities and the formation of corollary patterns in order to gain a deeper understanding of the underlying physical phenomena and the conditions that lead to the chaotic behaviour of discontinuous shear thickening (DST) fluids. This work consists of two major sec...

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Published: Swansea 2025
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Sandnes, B.
URI: https://cronfa.swan.ac.uk/Record/cronfa71080
first_indexed 2025-12-04T13:23:31Z
last_indexed 2025-12-05T18:13:28Z
id cronfa71080
recordtype RisThesis
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spelling 2025-12-04T13:28:36.0305093 v2 71080 2025-12-04 Spatiotemporal Instabilities in Discontinuous Shear Thickening Fluids 016c22005494b4c3e22b73a12ee35b08 PETER ANGERMAN PETER ANGERMAN true false 2025-12-04 The aim of this work is to study instabilities and the formation of corollary patterns in order to gain a deeper understanding of the underlying physical phenomena and the conditions that lead to the chaotic behaviour of discontinuous shear thickening (DST) fluids. This work consists of two major sections, computational and experimental. In the computational sections, we focus on the problem of rheochaos and aim to develop a minimal microstructural model required to reproduce aperiodic oscillatory behaviour in simple shear. We begin by presenting the first microstructural implementation of DST in Smoothed Particle Hydrodynamics (SPH). We demonstrate that locality in microstructure evolution combined with the characteristic rheology of DST materials yields an inherent spatial instability. We introduce a non-local com-ponent in microstructure evolution to obtain formation of frictional structures with a well-defined length scale. Analysis of competition between local and non-local components allowed us to identify spatial configuration as a key feature required to obtain aperiodic solutions. By tuning the parameter space to closely resemble realistic DST materials, we are able to reproduce rheochaotic oscillations closely resembling those reported in the literature, driven by transient cycles of emergence and dissipation in localised frictional structures. Application to realistic flow geometries reveals excellent performance, with our model being able to capture the problem of flow curve construction, the effects of confinement and inertia, and instabilities in Poiseuille flow. Our experimental work focuses on free surface flows. We report a new ’ridge’ flow instability in the inclined plane arrangement and identify the significant negative values of N2 as the driving mechanism. By employing a combination of trough and inclined plane measurements, we demonstrate that the inclined plane is a plausible tool for measurement of N2 in regimes where conventional methods are not readily applicable. E-Thesis Swansea Computational Fluid Dynamics, Non-Newtonian Fluids, Rheology 29 7 2025 2025-07-29 10.23889/SUThesis.71080 COLLEGE NANME COLLEGE CODE Swansea University Sandnes, B. Doctoral Ph.D EPSRC Doctoral Training Grant (DTG) EPSRC Doctoral Training Grant (DTG) 2025-12-04T13:28:36.0305093 2025-12-04T13:17:21.1983545 Faculty of Science and Engineering School of Engineering and Applied Sciences - Chemical Engineering PETER ANGERMAN 1 71080__35761__497b86729f7c448899beb3ea8bcd1dcc.pdf 2025_Angerman_P.final.71080.pdf 2025-12-04T13:23:16.6297777 Output 79278952 application/pdf E-Thesis – open access true Copyright: the author, Peter Angerman, 2025 Distributed under the terms of a Creative Commons Attribution 4.0 License (CC BY 4.0) true eng https://creativecommons.org/licenses/by/4.0/
title Spatiotemporal Instabilities in Discontinuous Shear Thickening Fluids
spellingShingle Spatiotemporal Instabilities in Discontinuous Shear Thickening Fluids
PETER ANGERMAN
title_short Spatiotemporal Instabilities in Discontinuous Shear Thickening Fluids
title_full Spatiotemporal Instabilities in Discontinuous Shear Thickening Fluids
title_fullStr Spatiotemporal Instabilities in Discontinuous Shear Thickening Fluids
title_full_unstemmed Spatiotemporal Instabilities in Discontinuous Shear Thickening Fluids
title_sort Spatiotemporal Instabilities in Discontinuous Shear Thickening Fluids
author_id_str_mv 016c22005494b4c3e22b73a12ee35b08
author_id_fullname_str_mv 016c22005494b4c3e22b73a12ee35b08_***_PETER ANGERMAN
author PETER ANGERMAN
author2 PETER ANGERMAN
format E-Thesis
publishDate 2025
institution Swansea University
doi_str_mv 10.23889/SUThesis.71080
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Chemical Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Chemical Engineering
document_store_str 1
active_str 0
description The aim of this work is to study instabilities and the formation of corollary patterns in order to gain a deeper understanding of the underlying physical phenomena and the conditions that lead to the chaotic behaviour of discontinuous shear thickening (DST) fluids. This work consists of two major sections, computational and experimental. In the computational sections, we focus on the problem of rheochaos and aim to develop a minimal microstructural model required to reproduce aperiodic oscillatory behaviour in simple shear. We begin by presenting the first microstructural implementation of DST in Smoothed Particle Hydrodynamics (SPH). We demonstrate that locality in microstructure evolution combined with the characteristic rheology of DST materials yields an inherent spatial instability. We introduce a non-local com-ponent in microstructure evolution to obtain formation of frictional structures with a well-defined length scale. Analysis of competition between local and non-local components allowed us to identify spatial configuration as a key feature required to obtain aperiodic solutions. By tuning the parameter space to closely resemble realistic DST materials, we are able to reproduce rheochaotic oscillations closely resembling those reported in the literature, driven by transient cycles of emergence and dissipation in localised frictional structures. Application to realistic flow geometries reveals excellent performance, with our model being able to capture the problem of flow curve construction, the effects of confinement and inertia, and instabilities in Poiseuille flow. Our experimental work focuses on free surface flows. We report a new ’ridge’ flow instability in the inclined plane arrangement and identify the significant negative values of N2 as the driving mechanism. By employing a combination of trough and inclined plane measurements, we demonstrate that the inclined plane is a plausible tool for measurement of N2 in regimes where conventional methods are not readily applicable.
published_date 2025-07-29T05:32:15Z
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score 11.089386

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