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Abstract: Fluidized bed systems are widely used in chemical and process engineering due to their excellent heat and mass transfer properties. Numerical modeling plays a crucial role in understanding and optimizing these systems, with the two-fluid model enhanced by the kinetic theory of granular flow (TFM-KTGF) and the coupled computational fluid dynamics-discrete element method (CFD-DEM) emerging as leading techniques. This study employs both models to simulate gas-solid interactions and evaluates their performance using a benchmark single-spout fluidized bed case validated against experimental data. Subsequently, the influence of particle presence on gas flow distribution through a non-uniform distribution plate is analyzed. The results show that the common assumption of proportional flow distribution based on the opening area fraction is inaccurate, particularly in the presence of particles. Both numerical models capture this behavior, with TFM-KTGF showing trends comparable to the coupled CFD-DEM approach but at significantly reduced computational cost. The findings highlight the importance of accounting for particle dynamics in distribution plate design and promote the TFM-KTGF approach as a promising alternative for large-scale simulations.
Keywords: fluidized bed, distribution plate, two-fluid model with kinetic theory of granular flow, coupled CFD-DEM, flow distribution
Published in DKUM: 09.12.2025; Views: 0; Downloads: 5
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Abstract: This editorial introduces the Special Issue of the Strojniški vestnik - Journal of Mechanical Engineering dedicated to the 30th anniversary of the Faculty of Mechanical Engineering as an independent member of the University of Maribor, and the 50th anniversary of the University of Maribor. The Faculty of Mechanical Engineering is one of the most successful members at the University of Maribor and is recognised for its excellence in education, research and collaboration with industry. Its history of development, from its early beginnings in 1959 to becoming an internationally active and research-driven institution, reflects a continuous commitment to technological progress and societal impact. The Special Issue presents a selection of articles covering applied fluid mechanics, advanced materials and metamaterials, manufacturing science, and biomedical modelling. The collected works combine experimental, numerical, and review-based approaches to address contemporary challenges in mechanical engineering. This publication not only highlights the scientific excellence achieved at the Faculty of Mechanical Engineering, University of Maribor, but also celebrates its enduring mission to connect knowledge, innovation and human creativity in shaping a sustainable and technologically advanced future.
Keywords: applied fluid mechanics, computational fluid dynamics (CFD), hydropower systems, advanced materials, metamaterials, triply periodic minimal surfaces (TPMS), biomedical modelling, inverse bioheat problem, intelligent toolpath generation, artificial intelligence in manufacturing
Published in DKUM: 08.12.2025; Views: 0; Downloads: 4
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Abstract: The present work focuses on the comparison of the capabilities of Blade Element Momentum Theory, with and without the high induction factor value model and Computational Fluid Dynamics modelling in relation to experimental measurements of the power coefficient for a model-sized horizontal axial wind turbine. Initially, an analytical investigation was performed to obtain the power coefficient curve. Furthermore, three-dimensional numerical simulations were performed, where a lot of effort was devoted to the preparation of a low y+ structured mesh. Analytical and numerical results of the power coefficient were compared with experimental results, which were obtained with our own conducted experiments in the wind tunnel. The most significant conclusions are that the classic BEM method deviates from measured data in the entire range of tip speed ratios, the BEM method with Spera correction predicts a significantly better agreement with experimental measurements compared to the classic BEM method, especially the part where the power coefficient decreases and finally that CFD computations can accurately predict the performance of wind turbines and compute the flow around an aerofoil of the blade.
Keywords: BEM method, CFD, measurements, wind turbine
Published in DKUM: 06.11.2025; Views: 0; Downloads: 3
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Abstract: V magistrskem delu je predstavljena numerična analiza procesa polnjenja farmacevtske vijale s suspenzijo, ki vsebuje enkrat nedeformabilne in drugič deformabilne mikrodelce. Glavni cilj simulacij je bil preučiti dinamiko tokovnega polja ter vpliv polnilnega procesa na gibanje in deformacijo delcev v tekočini. Uporabljena je bila metoda VOF za sledenje proste gladine med zrakom in vodo, dopolnjena z Lagrangevim pristopom za sledenje delcev. Porazdelitev nedeformabilnih ter deformabilnih delcev med in po polnjenju je zelo podobna, prav tako učinek usedanja. Rezultati pokažejo, da polnjenje vijale večinoma ni kritičen del proizvodnega procesa takšnih zdravil, saj so deformacije delcev minimalne.
Keywords: računalniška dinamika tekočin (CFD), VOF metoda, Lagrangevo sledenje delcev, deformabilni mikrodelci
Published in DKUM: 22.08.2025; Views: 0; Downloads: 41
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Abstract: In this work, we developed a numerical approach based on an experimental platform to determine the working conditions on a cryoplatform and to predict and evaluate the cryogenic printing of hydrogels. Although hydrogels have good biocompatibility, their material properties make it difficult to print them with high precision and shape fidelity. To overcome these problems, a cryogenic cooling platform was introduced to accelerate the physical stabilisation of each deposited layer during the printing process. By precisely controlling solidification (crystallisation), each printed material can withstand its own weight to maintain shape fidelity, and the porosity of the scaffolds can also be controlled more selectively. The thermophysical properties of gelatine hydrogels were investigated to gain a better understanding of the phase change upon freezing. The corresponding material properties and experimental observations of gelatine solidification served as the basis for developing a computational fluid model (CFD) to mimic the solidification of gelatine hydrogels using a cryoplatform at different process conditions and extruder speeds. The goal was to develop a tool simple enough to predict acceptable process conditions for printing gelatine hydrogels using a cryoplatform.
Keywords: gelatine, hydrogel, cryoprinting, CFD simulation, solidification modelling
Published in DKUM: 20.03.2025; Views: 0; Downloads: 12
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