- Title
- Theoretical, experimental and numerical studies on dynamic moisture migration within bulk solids
- Creator
- Chen, Jian
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2018
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Moisture migration is a common yet complex mechanism within moistened bulk solids. Such a phenomenon induces constant variation of bulk material properties, which can be beneficial or problematic during the storage, transport and handling of bulk materials. This research investigates this phenomenon and enhances the understanding of moisture migration within partially saturated bulk solids, with a particular focus on dynamic conditions. Firstly, the background of this research was introduced, and the fundamental concepts and impact of the research were briefly discussed. Some previous theoretical studies from both the microscopic and macroscopic scales were reviewed, as well as current progress in numerical modelling of moisture migration behaviours, such as computational fluid dynamics - discrete element method (CFD-DEM), and smooth particle hydrodynamics - discrete element method (SPH-DEM). The gap between these research and this topic was demonstrated. A detailed research plan, including the theory, experiments and simulation techniques, was proposed to study the phenomenon. Secondly, Theoretical modelling was performed to describe the constitutive moisture migration mechanism based on the classic Richards equation. The modelling considered the dynamic conditions of the bulk solids as well as the dynamic potential of water potential. The theoretical model gave the effect of many factors on the moisture migration. Thirdly, a number of typical bulk solids exhibiting moisture migration were selected for this study, and the fundamental material properties were initially tested. This included the particle size distribution, free drained saturation moisture content, and water particle density. Then, experimental studies were conducted to investigate the moisture migration of partially saturated bulk solids under dynamic conditions, with a purposely designed experimental system. The moisture migration of the bulk solids was correlated to the material’s properties and dynamic conditions. The experimental results were then compared against the theoretical predictions to validate the developed model. The experimental analysis also showed the effect of acceleration and particle size on moisture migration. Lastly, a numerical modelling frame was developed to couple DEM and SPH and to investigate the microscopic moisture migration. A number of numerical calibration tests were developed and performed to ensure the numerical model and associated parameters are able to reflect the physical moisture migration in reality. Results from numerical modelling showed a similar qualitative trend to the theoretical prediction and experimental observations.
- Subject
- bulk solids; moisture migration; partial saturation; modified Richards equation; SPH-DEM
- Identifier
- http://hdl.handle.net/1959.13/1392677
- Identifier
- uon:33443
- Rights
- Copyright 2018 Jian Chen
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 10 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 458 KB | Adobe Acrobat PDF | View Details Download |