Paulius Vilkinis doctoral dissertation defense

Author, Institution: Paulius Vilkinis, Lithuanian Energy Institute

Dissertation title: Investigation of flow dynamics and structure in channels with structured surfaces

Science area, field of science: Technological Sciences – Energy and Power Engineering, T006

Defense of the dissertation: 2020-01-24, 13:00, Lithuanian Energy Institute (Meeting Hall – AK-202 a.), Breslaujos st. 3, Kaunas, Lithuania.

Scientific Supervisor: – Dr. Nerijus Pedišius (Lithuanian Energy Institute, Technological Sciences, Energetics and Power Engineering, T006)

Dissertation Defence Board of Energetics and Power Engineering Science Field:

• Prof. Habil. Dr. Gintautas Miliauskas (Kaunas University of Technology, Technological Sciences, Energetics and Power Engineering, T006),
• Dr. Algis Džiugys (Lithuanian Energy Institute, Technological Sciences, Energetics and Power Engineering, T006),
• Prof. Dr. Algirdas Jasinskas (Vytautas Magnus University, Technological Sciences, Environmental Engineering, T004),
• Dr. Raimondas Pabarčius (Lithuanian Energy Institute, Technological Sciences, Energetics and Power Engineering, T006),
• Prof. Dr. Jacek Porozki (Poland Science Academy, Technological Sciences, Energetics and Power Engineering, T006).

The doctoral dissertation is available on the internet and at the library of Kaunas University of Technology (K. Donelaičio g. 20, Kaunas) and at Lithuanian Energy Institute (Breslaujos   g. 3, Kaunas).

Annotation:
Flow separation phenomena have a considerable impact on mass, momentum, and heat transfer processes in flowing fluids and their mixing processes. These phenomena are the main reason why separated flow remains a research object in engineering. Furthermore, they are a source for a deeper understanding of the internal mechanism of vortex formation, interaction, and disintegration. The aim of this work is to investigate fluid flow dynamics and structure in channels with abrupt cross-section changes and to determine the characteristics of recirculating flow depending on flow regime and channel geometrical parameters using experimental and numerical approaches.

By this work the knowledge of recirculation zone structure and length dynamics for different cavity types, depending on cavity geometrical parameters (H/h and L/h1) is improved. Also, determined dependencies and patterns of physical recirculation zone parameters for laminar and turbulent flow regimes. Revealed causes of the effect of channel expansion ratio (H/h) and Re for dynamics of recirculation zone length, which helps to explain the scattering of other authors’ results and suggest possible scaling for laminar and turbulent flow regimes.

Results of this work are significant for a large number of engineering problems where flow separation is induced by abrupt changes of channel cross-section, which can be analyzed as flows over cavities in a channel.

• Summary of the dissertation
• Dissertation (in Lithuanian)