EDUCATION AND RESEARCH TOPICS OF THE Ph.D. PROGRAM
Introduction
Environmental sciences are increasingly important, and they have a broad range of applications. We are specifically interested in the processes involving motion of a fluid, and the related properties of advection, dispersion and mixing within the fluid itself. In evoking environmental and geophysical fluid mechanics, one has to think in a very broad sense, including large-scale and small-scale processes, transport phenomena at the relevant scales, interaction between a dissolved phase and the carrying fluid, and the possible effect of mixing on the biological properties of the fluid. Thermodynamics and microphysics of the large-scale processes are part of the program. Finally a growing attention is being paid in the biological fluid mechanics, and the interaction between fluid dynamics and medical science. This new research topic will complete our field of interests. In this sense, the following research fields are included within the general definition given above:
Large scale motion in the oceans.
Large scale motion in the atmosphere.
Large scale motion in large reservoirs.
Small-scale processes (three-dimensional turbulent and mixing).
Interaction between physical and biological properties in environmental flows.
Transport phenomena in a flow field.
Transport phenomena in porous media.
Cardiovascular Fluid Mechanics
The study of large scale motion in the ocean is traditionally considered a field of interest of physical oceanography. Understanding the related physical processes (we also intend large sea basins, such as the Mediterranean Sea) is of crucial importance for driving strategic and political choices regarding the management of coastal areas. Physical oceanography represents a specific part of general fluid mechanics, and, for this reason, the study of this kind of phenomena requires a deep knowledge of basic and advanced geophysical fluid mechanics.
The analysis and understanding of large scale motion in the low atmosphere have a strong impact in the daily life of people. As an example, a common problem in the urbanized areas of north Italy during late fall and winter, is the thermal inversion and the related strong stably stratified flow field generally associated with smog, dramatically degrading the quality of air. The study of low-atmosphere dynamics is also important for the prediction of the concentration and distribution of aerosols and pollutants released in the air in industrial areas. This field also represents a special part of fluid-mechanics somewhat similar to the oceanography counterpart, although very different in other aspects.
The study of large scale motion in reservoirs, typically lakes, is of crucial importance for tracking the quality of water in populated areas: understanding the dynamics of plumes and jets in a neutral or in a stratified medium is fundamental in making accurate predictions of the fate of a pollutant or a contaminant released in the water body.
The main problems mentioned above are typically studied using large-scale models with a resolution ranging from the order of hundreds of meters to kilometres. Thus horizontal and vertical small scale mixing cannot be directly resolved by the model itself and need to be parameterize. It is worth noting that the quality of the results from large-scale simulations depends on many features (some of them developed further in this document); among them, a crucial aspect is the capability of the turbulence parameterization to correctly reproduce the small-scale mixing dynamics under complex-flow conditions, such as rotation, stratification and topographic effects.
The choice and, when needed, the improvement and the re-formulation of turbulence parameterization and closures to be used in conjunction with large-scale models require a deep knowledge of the underlying physics including the dynamics of turbulence. Hence, the study of small-scale processes per se, is essential to understand the physical mechanisms of mixing within the fluid under complex conditions the main drawback of the present turbulence parameterization, and to develop, whenever needed, new and more effective sub-grid schemes.
A very new field of research in environmental fluid dynamics is the study of interactions between a turbulent fluid field and biological species. Turbulence acts both on the large and small scales of motion. As a consequence, a passive particulate tends to be transported and mixed by the carrying flow field. In the case of an active particulate however, the mixing and advection properties of the flow field can affect the biological production. On one hand, mixing can enhance biological productivity at small scales and, on the other hand, coherent structures, such as vortices and jets, may limit and localize the production processes. The basic physics of the above mentioned problems is a necessary background for a PhD in Environmental Fluid Mechanics.
It is important to note that, by “transport phenomena” we intend those characterized by an interaction between different phases. The typical case is that of two-phase flows, where a diluted phase is transported within a carrying one (for instance water or air). Understanding and modeling transport phenomena is of great importance in environmental fluid dynamics: several points mentioned refer to this kind of phenomena more or less explicitly (dispersion of solid particulates, interaction between turbulence and biological species etc.). The mathematical and physical characterization of these phenomena is the basis for investigating applicative problems.
Education
The main objective is to train students in the field of Environmental Fluid Mechanics with special emphasis on basic fluid mechanics and the physics of large scale flows. Since the dissertation program will be carried out using the most up-to-date tools of analysis (for numerical simulations and for experimental analysis), the students will be ready to work in high-technology, using the theoretical and applicative foundations developed during the Ph.D. program.
The present program can work jointly with the Master in Oceanography program that is being initiated at the University of Trieste, in cooperation with the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS). Courses can be shared in mathematics, and geophysical fluid mechanics, a common part of physical oceanography. Since the two programs are different from each other (PhD program versus Master program), they are not competing against one another; furthermore, because they refer to two different topics (Geophysical and Environmental Fluid Mechanics the former and Oceanography the latter), they appear quite complementary. As an example, students who obtain a Master in Oceanography could be interested in continuing their training in physical oceanography and working on a research project in this field, and may be suitable candidates for the present PhD program.
The program is intended to train students for a variety of careers in research, teaching and high-technology, related to the applicative fields discussed above.
Depending on the student’s background and ability, research is initiated as soon as possible. The student, together with his advisor, identifies a dissertation research topic. The topic must be original and must represent the state of art of research in the field of interest. The research project can focus on a large scale application and/or on a fundamental study of fluid-mechanics helpful for understanding of physical processes observable in environmental and/or geophysical applications.
The following general areas have been identified:
1)Fundamental Fluid Mechanics
2)Meteorology, Climatology and Physics of Atmosphere
3)Physical Oceanography
The results of the research program are required to constitute material to be published on outstanding (ISI) international scientific journals. During the PhD program, the candidate will have gained experience in theoretical and applied fluid mechanics, familiarity with up-to-date techniques for the investigation and analysis of complex physical problems, which will be of great importance for future work in research centres and high-tech companies.
Qualifying elements
There are formal course requirements for the Ph.D. program. All students are required to attend course programs that will prepare them for their research. The students are expected to demonstrate proficiency in mathematic methods, fluid mechanics, computer science, physical oceanography, and low atmosphere dynamics.
Two kinds of courses are needed:
1)basic knowledge
2)advanced methods
The basic courses in basic must give the tools for understanding and analyzing the physical problems under investigation. These will focus on advanced mathematics, (partial diff. equation, numerical analysis, statistics), computer science, basic and advanced fluid mechanics, computational fluid mechanics, experimental techniques in fluid mechanics, geophysical fluid mechanics, physics of turbulence, and turbulence modeling.
The courses of advanced knowledge will focus on physical oceanography, dynamics of low atmosphere, full-scale measurements etc.
Ten courses of basic knowledge in fluid-dynamics and mathematics will be attended by the candidate during the first year. Seminar on particular aspects of fluid-mechanics will be attended during the second year. The following ten courses must be attended by the Ph.D. students:
- Fluid Mechanics I
- Numerical Methods
- Advanced Mathematical Methods
- Elements of Statistics
- Fluid Mechanics II
- Computational Fluid Dynamics
- Instability and Turbulence
- Geophysical Fluid Mechanics
- Physics of Ocean
- Physics of Atmosphere
The courses will comprise 30 hours, (3 hours per week for a total of 10 weeks) apart Elements of Statistics which will be of 15 hours distributed over 5 weeks.
For each course the student is required to prepare homeworks, to pass a mid-term exam and a final exam.
The courses are to be attended in Trieste. Alternatively, equivalent courses can be attended at foreign Universities belonging to the Program.
A qualifying exam consisting of a general discussion of the topics of the first year courses will be given early January at the end of the first year. Students who will not pass the exam will be invited to abandon the Ph.D. program.
The courses will be complemented by seminars given by members of the Ph.D. Committee or outstanding scientists coming from abroad, also belonging to Universities or Research Centres belonging to the Program. Additional seminars may be given by outstanding scientists invited from abroad. The students are required to attend at least 50% of the above listed seminars.
A qualifying exam consisting of a general discussion of the topics of the seminars attended by the students will be given at the end of the second years
The candidates will be supplied of a logbook which will contain the records of the courses and the seminars attended, the rank obtained in the exams and other useful information about their activity within the program.
Prerequisites
Students are required to have a 5-year bachelor degree or a master degree in one of the following areas:
Physics
Engineering
Mathematics
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