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Fluid Dynamics and Solid Transport in Thermal Flows

With this Ph.D. project, we propose an investigation into the dynamics of natural thermal flows typically encountered in industrial applications and manufacturing techniques, essentially thermal fluid motion driven by gravity and/or surface tension effects and related solid particle transport phenomena. Flows of thermo

Number of places

One

Opens

30 October 2018

Deadline

31 May 2019

Duration

36 months

Eligibility

The opportunity is open to Home, EU and International applicants, who meet the required University of Strathclyde eligibility criteria.  In particular the applicant must not have been awarded a previous Doctoral Degree.

In addition to the above, the applicant will hold, or in the process of obtaining, an integrated Master’s degree or equivalent in Mechanical Engineering, Chemical Engineering, Materials Science, Materials Engineering, Metallurgy, Aeronautical or Aerospace Engineering, Physics, or another discipline related to the proposed research projects.

Experience with OpenFoam or Ansys Fluent will be appreciated (but it is not strictly required).

Project Details

With this Ph.D. project, we propose an investigation into the dynamics of natural thermal flows typically encountered in industrial applications and manufacturing techniques (e.g., thermal processing of metal alloys and organic emulsions or suspensions, techniques for material solidification or crystallization, etc.), essentially thermal fluid motion driven by gravity and/or surface tension effects and related solid particle transport phenomena. Flows of thermogravitational and thermocapillary nature will be considered in various well-defined geometrical models, under various heating conditions, for a range of different fluids (including Newtonian and complex fluids) and possible combinations of all these variants. Starting from relatively simple test cases, the student will progressively consider configurations and problems with an increasing degree of complexity, up to characterizing the complete hierarchy of fluid-dynamic bifurcations and identifying spatiotemporal regimes which are still completely unknown. Related solid particle transport phenomena (especially sedimentation and inertial aggregation behaviours, which play a fundamental role in many materials processing techniques) will be studied by adding tracers (of various densities and sizes) to the considered liquids.

Remarkably, these studies, will not be limited to the cases in which these types of convection (thermogravitational or thermocapillary) act separately. Significant effort will be also devoted to elucidate the possible “interplay” of several effects in situations where driving forces of different nature (gravity and surface tension) are simultaneously responsible for the generation of fluid motion. This subject (hybrid or mixed convection) is of a particular importance as the identification of the most dominant mechanism and/or the mutual interference of different mechanisms involved with a comparable intensity, may help the researchers in elaborating rational guidelines relating to physical factors that can increase the probability of success in the above-mentioned practical technological processes.

The research will involve the application of both numerical and experimental techniques. For the experiments dealing with surface-tension driven flows, in particular, the student will take advantage of the recently developed (Autumn 2015) microscale facility, available at the James Weir Fluid Labs, in which it is possible to create floating zones and liquid bridges in well-controlled thermal conditions. The student will also be trained to use laser-based and optical techniques for flow visualization. From a numerical-simulation standpoint, the project will benefit from a set of (already validated) numerical codes for the solution of the governing fluid-dynamics equations in their “complete”, non-linear, time-dependent and three-dimensional, formulation(with a variety of possible boundary conditions and involved physical forces). It is expected that the student will critically use such tools, comparing numerical and experimental results, and feeding back the supervisor (codes developer) with relevant information for the improvement or refinement of the underlying mathematical models(especially for the modeling of thermal convection in nanofluids and non-Newtonian liquids, a poorly known subject still requiring much investigation).

[1] M. Lappa, (2014), Stationary Solid Particle Attractors in Standing Waves, Physics of Fluids, 26(1), 013305 (12 pages)

[2] M. Lappa (2012), Rotating Thermal Flows in Natural and Industrial Processes, John Wiley & Sons, Ltd (2012, Chichester, England).

[3] Francisco J. Galindo-Rosales , Laura Campo-Deaño , Patrícia C. Sousa , Vera M. Ribeiro ,Mónica S.N. Oliveira , Manuel A. Alves, (2014), Fernando T. Pinho, Viscoelastic instabilities in micro-scale flows, Experimental Thermal and Fluid Science, 59, 128–139

Funding Details

Please note the project is unfunded, therefore would be suitable to eligible applicants with self funding, or with the possibility of other sources of funding.

However, funding may be available for Home (UK) students who meet the requirements to be selected in the framework of the "Doctoral Training Partnership" of the University of Strathclyde with Engineering and Physical Sciences Research Council (EPSRC)

Further information

From a theoretical point of view, training will be provided to illustrate the 1) genesis of such flows, 2) governing parameters, 3) scaling properties, 4) typical flow structure and stability concepts. From a practical standpoint, the student will be trained to use available numerical tools. Accordingly, relevant information will also be provided on the underlying numerical techniques. From an experimental standpoint, the student will be trained to investigate thermal flow in different configurations (horizontal layers, open and closed geometries, shallow and tall cavities, cubical and parallelepipedic slots, annular configurations, cylindrical enclosures, floating zones and liquid bridges), both at the macroscale and at a smaller scale (using the microscale device). In the first case he/she will learn to characterize flows where the effect of gravity is dominant, while in the second, he/she will be studying flows where surface-tension gradients are the primary driving force. Such a wide spectrum investigation will provide the student with a solid background to cope with more complex problems of technological interest. Furthermore, it is expected that, by virtue of the combined numerical-experimental approach, the student will learn how to feed new vital information back into the mathematical models at the basis of the aforementioned numerical tools