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Projects / Programmes source: ARIS

Transient two-phase flows

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Periods
January 1, 2015 - December 31, 2021
Research activity

Code Science Field Subfield
2.13.00  Engineering sciences and technologies  Process engineering   

Code Science Field
T350  Technological sciences  Chemical technology and engineering 

Code Science Field
2.03  Engineering and Technology  Mechanical engineering 
Keywords
transient two-phase flow, principles of complex fluid dynamics, flow-induced materials problems, fluid-structure interaction
Evaluation (rules)
source: COBISS
Evaluation of bibliographic research performance indicators according to ARIS methodology
Citations Citations for bibliographic records in COBIB.SI that are linked to records in citation databases
source: WoS source: Scopus source: COBISS
Researchers (27)
no. Code Name and surname Research area Role Period No. of publications
1.  54918  Izaz Ali  Process engineering  Junior researcher  2021  5 
2.  03923  PhD Anton Bergant  Process engineering  Researcher  2015 - 2021  392 
3.  05912  PhD Andrej Bombač  Process engineering  Researcher  2017 - 2021  222 
4.  36852  Matic Cotič    Technical associate  2015 - 2021  23 
5.  38848  PhD Tadej Dobravec  Process engineering  Researcher  2021  55 
6.  32071  PhD Jurij Gregorc  Materials science and technology  Researcher  2015 - 2021  89 
7.  30833  PhD Umut Hanoglu  Process engineering  Researcher  2017 - 2021  50 
8.  37412  PhD Vanja Hatić  Process engineering  Researcher  2019 - 2021  43 
9.  21381  PhD Miha Kovačič  Manufacturing technologies and systems  Researcher  2019 - 2021  245 
10.  33584  PhD Qingguo Liu  Process engineering  Researcher  2017 - 2021  34 
11.  31564  PhD Matevž Luštrik  Pharmacy  Researcher  2015 - 2018  46 
12.  36364  PhD Boštjan Mavrič  Process engineering  Researcher  2017 - 2020  105 
13.  36464  PhD Tijan Mede  Materials science and technology  Researcher  2021  13 
14.  35031  PhD Katarina Mramor  Process engineering  Researcher  2017 - 2021  60 
15.  04471  PhD Matjaž Perpar  Process engineering  Researcher  2015 - 2021  128 
16.  36399  PhD Jernej Pirnar  Engineering sciences and technologies  Researcher  2015 - 2018  19 
17.  22649  PhD Janez Povh  Computer intensive methods and applications  Researcher  2020 - 2021  341 
18.  51900  Khush Bakhat Rana  Process engineering  Junior researcher  2019 - 2021  13 
19.  01371  PhD Zlatko Rek  Process engineering  Researcher  2015 - 2021  218 
20.  52366  Zdenka Rupič    Technical associate  2021  0 
21.  04101  PhD Božidar Šarler  Process engineering  Head  2017 - 2021  1,103 
22.  23018  PhD Robert Vertnik  Manufacturing technologies and systems  Researcher  2019 - 2021  222 
23.  53510  Gašper Vuga  Process engineering  Junior researcher  2019 - 2021  16 
24.  25450  PhD Nikola Vukašinović  Mechanical design  Researcher  2021  207 
25.  50585  Matjaž Zadnik  Process engineering  Junior researcher  2017 - 2018  0 
26.  37776  PhD Rizwan Zahoor  Process engineering  Researcher  2018 - 2021  42 
27.  03544  PhD Iztok Žun  Process engineering  Researcher  2015 - 2016  540 
Organisations (1)
no. Code Research organisation City Registration number No. of publications
1.  0782  University of Ljubljana, Faculty of Mechanical Engineering  Ljubljana  1627031  29,252 
Abstract
The primary drive in the technical advances of heat and mass transfer being sought is to develop a deeper understanding of the physics of multiphase flow, and having acquired that insight, to develop appropriate mathematical models to predict the phenomena involved. Next, some if not all of the models will need to be incorporated into appropriate software (namely CMFD) ready for testing and validation against experimental data. We intend to continue our research actions organized in three thrust areas: The principles of complex fluid dynamics, Flow-induced materials problems, and Fluid-structure interaction. The ultimate goal is to contribute both, to basic science searching for the first principles within the scope of these three thrust areas as well as to resolve some industrial problems that are already defined in contracts with the industry.   Binary mixtures that have a coexistence between the two phases: solid-liquid, solid-gas, liquid-gas and liquid-liquid are regarded as complex fluids. They exhibit unusual mechanical responses to applied stress or strain due to the geometrical constraints that the phase coexistence imposes. Their mechanical properties can be attributed to characteristics such as high disorder, caging, and clustering on multiple length scales. In all two-phase fluids, the recognizable features of a complex system emerge when the individual phases are allowed to interact, and the interaction strength is gradually increased. The main focus under this section is going to be on indicators of flow instability, utilizing both experimentation and numerical simulation. Two experimental setups are envisaged: mini manifold system and a system for gas jet breakup studies due to Kelvin-Helmholtz instabilities. It is envisaged that gas-liquid and solid-gas flows considered will not be restricted to simple geometry only but will be oriented towards industrial application’s, like forced mixing in stirred vessels, trickle bed reactors and fluidization of solid particles in Wurster chamber.   The objective of flow-induced materials problems is to further investigate unsteady friction effects on the magnitude and timing of pressure pulses during column separation events in industrial applications.   Medical modelling and simulation is envisaged under fluid-structure interaction studies. Fluid - Structure Interaction numerical method is expected for partial upper airway collapse analysis as well as air stream coupling with the soft tissue vibration. A systematic research is expected to reveal the generic relationships, which are important for 3D physiological phenomena. The patient specific scans will be provided by the collaborating clinicians, who are dealing with human airway problems on a daily basis   In order to validate CFD codes, the specific problems are going to be chosen searching for generic principles of complex fluid dynamics simulation. The aim is to range commercial codes of applicability to selected industrial problems.
Significance for science
Scientific significance of the topic: Multiphase flow is a subject distinct, and much more difficult than single phase fluid mechanics and heat transfer. This is because while the starting principles are the same (i.e., the conservation of mass, momentum, and energy), the presence of coupled fluid motions, interacting through the unspecified geometry of the interfaces, requires a whole new scientific methodology for understanding, as well as a whole new engineering apparatus for practical applications. Even simple cases reveal multiphase flows as a class of non-linear adaptive systems, an immense frontier of science in the 21st century (Science, 1999).   Current nature of the initial hypothesis and methodological adequacy or design of research: Our ability to predict the behavior of multiphase flows contains a limiting factor in scaling, in analyzing heat transfer systems, in developing new technologies, in analyzing chemical reactors, in avoiding and managing industrial hazard to prevent accidents. As an illustration to tasks 1 and 2 of the proposed programme (not to mention the importance of medical modelling), one of the most important problems in the designing of new production processes is the definition of the scaling rules, which make it possible to extrapolate the results obtained from small-scale laboratory set-up to real-size complex industrial system. In the case of devices operating multiphase flows, a major difficulty namely arises from the occurrence, at some critical size and/or range of parameters, of unexpected phenomena resulting from the collective dynamics of a great number of dispersed elements, such as bubbles, drops or particles or interfacial instability in case of separated flow.   A clear idea and quality of objectives: A few important examples are going to be studied that provide flow instabilities, large-scale motion, segregation or preferential accumulation of phases, which induce drastic changes in the overall hydrodynamics and consequently the expected performance of technological processes. The concept is clear: the selected transitional phenomena in a two-phase flow will be treated in the light of the complex dynamics of fluid flow in search for the first principles. Special emphasis will be also devoted to the interaction of fluid-structure, the field of CFD, which opens great opportunities for multidisciplinary studies in conjunction with the medicine.The only conceivable methodology for success in achieving further scientific development is a coherent and tight integration of theory, modelling, and simulation (TMS) with experimentation (E) and resultant data which is the key principle of the proposed programme .   Original (new) expected results: Mechanical properties of two-phase flows are expressed in characteristics such as high level of entropy, and grouping on several local scales. The identifiable characteristics of complex systems occur when distinct interaction of the individual phases is allowed and gradually intensifies. The hierarchy of two-phase flow will be treated as the product of a dynamic system, prone to change, and not just the structural framework, where it divides the components located to interact with one another. We expect the prediction of such "phase changes", such as the transition from bubbly to slug or annular flow, with the help of computer simulations based on the first principles of the fluid dynamics (the basic transport equations). Successful scale separation will be accompanied by further development of the integrated numerical modeling. One of the objectives in networking between different recognized laboratories under the umbrella of the ViR2AL is to develop an extensive flow regime and phenomenon based flow pattern map, a so-called smart flow pattern map. Such a smart flow pattern map will not only provide information on the flow pattern but also have embedded prediction methods for other flow properties such as void fraction, film thickness, etc. for
Significance for the country
Direct significance for businesses and publicly-provided services: Multiphase flow systems are crucial in most sectors of the process industry, such as chemical, biochemical, food, pharmaceutical, paper, and hydrocarbon production. There are also applications in aerospace, land transport, and power generation. All these are traditionally strong industries in the EU and account for a major part of economic turnover. For example, the The EU chemical industry provides a significant contribution to EU net exports. It is one of the European Union’s most international, competitive and successful industries, connected to a wide field of processing and manufacturing activities. The output of the chemical industry, which includes all 28 EU member states covers a wide range of chemical products, supplies virtually all sectors of the economy and provides 20% of the world production, with a turnover about 558 billions EUR with 1.2 millions of employees and strong trade surplus (the latest statistics date from 2013, http://www.cefic.org/Facts-and-Figures/). But in order to maintain this competitiveness the EU must retain and enhance its technological advantage by developing new production methods and innovative materials, while at the same time ensuring that such development is environmentally friendly and conforms to the prevalent cleanliness and safety policies.   Significance for development of research (sub)segments in short supply: Similar trends can be shown for pharmaceutical and chemical industry in Slovenia. To ensure the competitiveness or even technological advantage, Slovenia is forced to develop new production methods and innovative materials in a sustainable manner. There is no doubt, that in the future the miniaturisation of technical equipment will be the most important task in engineering science. The reductions of the material and energy consumption, including the reduction in environmental pollution, are only some benefits of smaller components. Such a development is possible only when based on sound theoretical and empirical analytical tools which by no doubt includes also the prediction of transient characteristics of multiphase processes.   Potential impacts and effects of results: The research group is well involved in industrial applications, currently having direct contracts with the following companies: Rhodia (Solvay), France (gas-liquid interface instability) Lek (Sandoz Group), Slovenija (gas-liquid forced mixing) Gorenje, Slovenija (rational energy use in kitchen appliances) Energetiko Ljubljana, Slovenija (heat losses in wet porous insulation) Litostroj Power (unsteady skin friction modelling in hydraulic piping systems) University Medical Center Ljubljana (OSAHS) Faculty of Pharmacy, University of Ljubljana (peletizacija) Dissemination: Faculty of Mechanical Engineering, University of Ljabljana, second and third Bologna cycle Virtual International Research Institute of Two-Phase Flow and Heat Transfer (see Attachment ViR2AL)
Most important scientific results Annual report 2015, interim report
Most important socioeconomically and culturally relevant results Annual report 2015, interim report
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