Numerical Simulation of Polymer-Particle Adsorption and Flocculation Dynamics for Nuclear Waste Separations

In nuclear waste processing, management of multiphase sludge waste is critical to on-going operations aimed at transporting that waste (as particle-laden water flows) to interim storage facilities. Important processes such as dewatering, containment and encapsulation require procedures wherein waste particulates are separated through settling. Sellafield Ltd has been exploring the potential of flocculation techniques, where small concentrations of high-molecular-weight polymers are added to particle-laden flows to separate non-settling fine solids, as a promising method to instigate settling. The dynamics associated with these processes are poorly understood. <br /> <br /> This project will be a collaboration between the Leeds nuclear group and Sellafield Ltd and will investigate the underpinning polymer-particle adsorption and subsequent flocculation/aggregation dynamics using first principles numerical simulation. Non equilibrium Langevin dynamics will be used to predict the interaction of polymers with simulated waste material, modelled as fully-resolved particles using an immersed boundary method. Relevant flow conditions such as shear and isotropic turbulence will be predicted using high-accuracy direct numerical simulation. Machine learning will also be used to augment the predictive capabilities and to limit the number of high computational cost simulations required. <br /> <br /> A full mechanistic understanding of the particle-polymer systems will help inform safe industrial practice, and contribute to waste management and clean-up through innovations that can be applied on nuclear sites and that are clearly socially desirable and in the public interest. These techniques are also relevant in the minerals industry and in general water treatment applications. The research student will work closely with a postdoctoral researcher and other PhD students working in similar areas, and in particular with a PhD student undertaking complementary experimental work. The project will be supervised by staff at the University and Sellafield Ltd.

<p style="margin-bottom:11px">Langevin dynamics alongside the finitely-extensible nonlinear elastic (FENE) dumbbell model will be used to simulate polymers as macromolecular chains of interacting beads. An existing code will be extended to include van der Waals and electric double layer interactions, as well as the capability to handle non-spherical particles. Preliminary investigations will be performed to determine the role of the&nbsp; FENE&nbsp; interaction&nbsp; strength, bending rigidity, steric&nbsp; interactions and ionic&nbsp; strength on single-particle adsorption efficiency. Analysis of these interactions will provide insight into processes such as steric stabilisation, in which the polymers shield the particle and mitigate further flocculation. Multi-particle interaction studies will be performed in order to simulate flocculation. Results will be validated against experimental findings from a project which is already underway and will run alongside the present study. Analysis of the adsorption mechanism on the particle-scale will be used to optimise flocculation, and to predict responses in aggregate behaviour such as radius of gyration, porosity and fractal dimension. Since the flocculation response relies on a large parameter-space configuration, to limit the number of simulations needing to be performed, machine learning will be used in which a predictive artificial neural network will be trained using data generated from the study predictions.</p> <p style="margin-bottom:11px"><a href="https://fluid-dynamics.leeds.ac.uk/"><strong>EPSRC Centre for Doctoral Training in Fluid Dynamics</strong></a></p>

<p>Formal applications for research degree study should be made online through the&nbsp;<a href="https://www.leeds.ac.uk/research-applying/doc/applying-research-degrees">University&#39;s website</a>. Please state clearly in the Planned Course of Study section that you are applying for <em><strong>EPSRC CDT Fluid Dynamics</strong></em> and in the research information section&nbsp;that the research degree you wish to be considered for is <em><strong>Numerical Simulation of Polymer-Particle Adsorption and Flocculation Dynamics for Nuclear Waste Separations</strong></em> as well as&nbsp;<a href="https://eps.leeds.ac.uk/chemical-engineering/staff/177/professor-michael-fairweather">Professor Michael Fairweather</a> as your proposed supervisor.</p> <p>If English is not your first language, you must provide evidence that you meet the University&#39;s minimum English language requirements (below).</p> <p><em>As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education. Across all Faculties we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+ and people with disabilities. Applicants will always be selected based on merit and ability.</em></p> <p class="MsoNoSpacing">Applications will be considered after the closing date for applications. &nbsp;Potential applicants are strongly encouraged to contact the supervisors for an informal discussion before making a formal application. &nbsp;We also advise that you apply at the earliest opportunity as the application and selection process may close early, should we receive a sufficient number of applications or that a suitable candidate is appointed.</p> <p>Please note that you must provide the following documents in support of your application by the closing date of 3 April 2023:</p> <ul> <li>Full Transcripts of all degree study or if in final year of study, full transcripts to date</li> <li>Personal Statement (the template can be found in the &lsquo;How to Apply&rsquo; section on the <a href="https://fluid-dynamics.leeds.ac.uk/">EPSRC CDT Fluid Dynamics</a> website)</li> <li>CV</li> <li>Funding information:&nbsp; EPSRC CDT Fluid Dynamics</li> </ul>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.

<p class="MsoNoSpacing">A highly competitive EPSRC Centre for Doctoral Training in Fluid Dynamics studentship in partnership with Sellafield Ltd, consisting of the award of fees with a maintenance grant (currently &pound;17,668&nbsp;for academic session 2022/23)&nbsp;for 4&nbsp;years.<br /> <br /> This opportunity is open to all applicants, with a very small number of awards for Non-UK nationals. All candidates will be placed into the EPSRC Centre for Doctoral Training in Fluid Dynamics Studentship Competition and selection is based on academic merit.<br /> <br /> <strong>Important:</strong>&nbsp; Any costs associated with your arrival at the University of Leeds to start your PhD including flights, immigration health surcharge/medical insurance and Visa costs are <strong>not</strong> covered under this studentship.</p> <p class="MsoNoSpacing">Please refer to the&nbsp;<a href="https://www.ukcisa.org.uk/">UKCISA</a>&nbsp;website for&nbsp;information regarding Fee Status for Non-UK Nationals.</p>

<p>For further information about this project, please contact Professor Michael Fairweather: e:&nbsp;<a href="mailto:m.fairweather@leeds.ac.uk">m.fairweather@leeds.ac.uk</a>&nbsp;or the EPSRC CDT Fluid Dynamics Centre Manager: e:&nbsp;<a href="mailto:fluid-dynamics@leeds.ac.uk">fluid-dynamics@leeds.ac.uk</a></p> <p>For further information about your application, please contact Doctoral College Admissions: e:&nbsp;<a href="mailto:phd@engineering.leeds.ac.uk">phd@engineering.leeds.ac.uk</a><br /> &nbsp;</p>