Mesoscale Simulations of Particulate Flows with Parallel Distributed Lagrange Multiplier Technique

Fluid particulate flows are common phenomena in nature and industry. Modeling of such flows at micro and macro levels as well establishing relationships between these approaches are needed to understand properties of the particulate matter. We propose a computational technique based on the direct numerical simulation of the particulate flows. The numerical method is based on the distributed Lagrange multiplier technique following the ideas of Glowinski et al. (1999). Each particle is explicitly resolved on an Eulerian grid as a separate domain, using solid volume fractions. The fluid equations are solved through the entire computational domain, however, Lagrange multiplier constrains are applied inside the particle domain such that the fluid within any volume associated with a solid particle moves as an incompressible rigid body. Mutual forces for the fluid-particle interactions are internal to the system. Particles interact with the fluid via fluid dynamic equations, resulting in implicit fluid-rigid-body coupling relations that produce realistic fluid flow around the particles (i.e., no-slip boundary conditions). The particle-particle interactions are implemented using explicit force-displacement interactions for frictional inelastic particles similar to the DEM method of Cundall et al. (1979) with some modifications using a volume of an overlapping region as an input to the contact forces. The method is flexible enough to handle arbitrary particle shapes and size distributions. A parallel implementation of the method is based on the SAMRAI (Structured Adaptive Mesh Refinement Application Infrastructure) library, which allows handling of large amounts of rigid particles and enables local grid refinement. Accuracy and convergence of the presented method has been tested against known solutions for a falling sphere as well as by examining fluid flows through stationary particle beds (periodic and cubic packing). To evaluate code performance and validate particle contact physics algorithm, we performed simulations of a representative experiment conducted at the University of California at Berkley for pebble flow through a narrow opening

Ukraine from the perspective of polish reporters

Celem pracy było przeanalizowanie zawartości polskich czasopism społeczno-politycznych „Polityka”, „Newsweek Polska”, „Wprost”, „Rzeczpospolita”, w szczególności artykuły Michała Kacewicza, Pawła Pieniążka i Ziemowita Szczerka dla określenia specyfiki problematyki publikacji o Ukrainie w czołowych czasopismach polskich iustalenia przemian wizerunku Ukrainy i Ukraińców w Polsce.Problematykę pracy dyplomowej: potrzeba eksploracji przestrzeni medialnej Polski, która ma tendencję do kreowania pewnego wizerunku Ukrainy i Ukraińców, a tym samym programowaniu pewnej oceny stosunku społeczeństwa polskiego w stosunku do ukraińskiego.Umiejscowienie problematyki w literaturze naukowej: źródłami do badań są środki masowego przekazu: gazety, czasopisma, artykuły, podcasty radiowe; podręczniki szkolne, wypowiedzi partii politycznych i organizacji publicznych, włącznie z przemówieniami polityków i inne.Zastosowano następujące metody: metoda naukowej abstrakcji, analizy i syntezy, indukcja i dedukcja, połączenie pojęć historycznych i logicznych, analiza ilościowa, podejście systemowe, analiza treści, analiza zdarzeń,analiza treści.Efekt pracy: Autorka przedstawiła charakterystykę obrazu Ukrainy w przestrzeni medialnej, kulturze i społeczeństwie polskim w latach 1991-2020. Zaprezentowała wizerunek Ukrainy od Majdanu do Donbasu w pracach Michała Kacewicza, zbadała i przedstawiła konflikt we wschodniej Ukrainie w pracach Pawła Pieniążka, zilustrowała obraz Ukrainy w kontekście kulturowym w pracach Ziemowita Szczerka.Wnioski: Na podstawie przedstawionej pracy można argumentować, że po przeczytaniu tej pracy można dowiedzieć się jaka jest wizja Ukrainy w systemie komunikacji społeczno-politycznej Polski oraz czynniki, które kształtują wizerunek Ukraińców w polskiej przestrzeni medialnej.The purpose of the work was to analyze the content of Polish socio-political magazines "Polityka", "Newsweek Polska", "Wprost", "Rzeczpospolita", in particular articles by Michał Kacewicz, Paweł Pieniążek and Ziemowit Szczerek to define the specificity of the issue of publications about Ukraine in leading Polish magazines and to establish changes the image of Ukraine and Ukrainians in Poland.The subject of the diploma thesis: the need to explore the media space of Poland, which tends to create a certain image of Ukraine and Ukrainians, and thus to program a certain assessment of the attitude of Polish society to Ukrainian.Positioning of the problem in the scientific literature: sources for research are the mass media: newspapers, magazines, articles, radio podcasts; school textbooks, statements by parties and public organizations, including statements by politicians and others.The following methods were applied: method of scientific abstraction, analysis and synthesis, induction and deduction, combination of historical and logical approaches, quantitative analysis, systems approach, content analysis, event analysis, content analysis.Effects of work: The author presents the characteristics of the image of Ukraine in the media space, culture and Polish society in the years 1991-2020. She presented the image of Ukraine from Maidan to Donbas in the works of Michał Kacewicz, discussed the presentation of the conflict in eastern Ukraine in the works of Paweł Pieniazek, and illustrated the image of Ukraine in a cultural context in the works of Ziemowit Szczerek.Conclusions: On the basis of the presented work, it can be argued that after reading this work, one can find out the image of Ukraine in Poland's social and political communication system and the factors that shape the image of Ukrainians in the Polish media space

Numerical studies of flow over a sill: sensitivity of the non-hydrostatic effects to the grid size

A non-hydrostatic terrain-following model in cross sectional form is applied to study the processes in the lee of a sill in an idealized stratified fjord during super-critical tidal inflow. A sequence of numerical studies with horizontal grid sizes in the range from 100 to 1.5625 m are performed. All experiments are repeated using both hydrostatic and non-hydrostatic versions of the model, allowing a systematic study of possible non-hydrostatic pressure effects and also of the sensitivity of these effects to the horizontal grid size. The length scales and periods of the internal waves in the lee of the sill are gradually reduced and the amplitudes of these waves are increased as the grid size is reduced from 100 down to 12.5 m. With a further reduction in grid size, more short time and space scale motions become superimposed on the internal waves. Associated with the internal wave activity, there is a deeper separation point that is fairly robust to all parameters investigated. Another separation point nearer to the top of the sill appears in the numerical results from the high-resolution studies with the non-hydrostatic model. Associated with this shallower separation point, an overturning vortex appears in the same set of numerical solutions. This vortex grows in strength with reduced grid size in the non-hydrostatic experiments. The effects of the non-hydrostatic pressure on the velocity and temperature fields grow with reduced grid size. In the experiments with horizontal grid sizes equal to 100 or 50 m, the non-hydrostatic pressure effects are small. For smaller grid sizes, the time mean velocity and temperature fields are also clearly affected by the non-hydrostatic pressure adjustments