Papers by Keyword: Numerical Modeling

Abstract: The article considers the use of numerical methods in the SCILAB environment for modeling particle trajectories under the influence of various physical forces: gravity, electromagnetism and friction. The simulations conducted allowed us to study the dynamics of particle motion in three-dimensional space under various conditions, in particular the influence of forces on changing trajectories and stabilizing motion. The results obtained demonstrate the effectiveness of using the SCILAB software as a tool for numerical modeling of complex physical systems, which ensures the accuracy of calculations and clarity of visualization. It should also be noted that the use of such approaches allows us to study particle motion in various fields of science and technology, in particular in physics, engineering and systems analysis. Numerical methods implemented in SCILAB provide flexibility in taking into account the initial conditions and parameters of the system, opening up prospects for further research into complex interactions in multicomponent systems.

Abstract: Phosphogypsum storage poses a major environmental challenge for countries engaged in chemical fertilizer production due to the polluting nature of this industrial byproduct. To promote more sustainable waste management, mining companies are exploring alternative uses, including the construction of sludge retention dikes for liquid effluent containment. In this context, the Gafsa Phosphate Company initiated a project to build sludge retention dikes using quarry waste to store phosphogypsum, with potential applications in civil engineering. This study presents a numerical investigation of the mechanical behavior of sludge retention dikes constructed from quarry waste near Metlaoui City in southwestern Tunisia. Two complementary approaches were employed: the finite element method (FEM), using a plane strain model with the Mohr–Coulomb constitutive law, and the limit equilibrium method (LEM) to cross-validate stability results. Geotechnical parameters for both the foundation soil and dike materials were derived from in-situ and laboratory investigations. The analysis focused on optimizing slope geometry to ensure an adequate factor of safety by assessing the influence of slope angle and sludge height on dike stability before and after basin filling. For a slope inclination of 2V:1H, the factor of safety exceeded 1.4 using FEM and reached approximately 1.5 with LEM following sludge deposition. After deposition, the factor of safety increased on the upstream side to 5.55 and decreased on the downstream side to values ranging from 1.55 to 1.25, depending on the sludge height. Despite this reduction, all configurations maintained a factor of safety above 1.2, indicating a globally stable structure. Furthermore, steeper slope configurations were associated with lower factors of safety, highlighting the critical role of slope design in ensuring the overall stability of sludge retention dikes.

Abstract: The Eco-Resort area at Raja Ampat is frequently impacted by extreme waves, particularly during the west monsoon, increasing the risk of abrasion and damage to ecosystems and infrastructure. A detached hexareef breakwater configuration was designed to reduce wave height while maintaining coastal aesthetics, as the site is an eco-friendly tourism area. The data used included tidal observations, bathymetry and topography surveys, wind and wave data, and hexareef formation data. The configuration was designed based on the beach response index, leading to periodic tombolo formation. Four configuration alternatives were developed based on freeboard (f) values under the HWS (Highest Water Springs) condition. Numerical modeling using Delft3D-WAVE assessed wave reduction effectiveness for each alternative. Results showed wave reductions for two significant wind and wave directions - North and Northwest - as follows: 24% and 33% for Alternative 1 (f = -1.018 m), 46% and 55% for Alternative 2 (f = -0.518 m), 66% and 71% for Alternative 3 (f = -0.218 m), and 72% and 77% for Alternative 4 (f = -0.018 m). Alternative 3 was chosen because its performance was only 6% lower than Alternative 4 (the most effective); however, it has a submergence value that is more suitable for maintaining coastal aesthetics.

Abstract: This study investigates the piezoelectric properties of a composite comprising polar hydroxyapatite (HA) and BaTiO₃ using an analytical model. The analysis covers the piezoelectric coefficients d₃₃ ​and d₃₁, and the specific acoustic impedance. The findings reveal that HA exhibits an unconventional d₃₃​ behavior, while the composite demonstrates a decrease in d₃₁​ and an increase in d₃₃​, with minimal BaTiO₃ content achieving d₃₃​ values similar to those of human bone (< 1 pC/N). Additionally, the d₃₁ coefficient of HA showed an unconventional behavior, highlighting its potential usage in the transverse direction. The impedance also increases from 23.5 MRayls to 31.5 MRayls, which improves acoustic wave transmission for medical imaging and therapeutic devices. These results highlight the composite's promise for bone regeneration, implantable ultrasound transducers, and energy harvesting applications.

Abstract: This study describes the validation and verification of a two-dimensional numerical wave channel with a Submerged Horizontal Plate (SHP). The SHP is a fixed, submerged structure with a dual function: it acts as a breakwater and as a wave energy converter. To carry out the validation and verification procedures for the computational modeling, experimental and numerical results obtained from the literature were used. A relative error of 2.14% for the maximum axial velocity below the SHP was obtained in the validation, while an average absolute error of 0.0043 m/s for the axial velocity variation below the SHP was identified in the verification. Therefore, it can be inferred that the validation and verification stages were carried out successfully. So, the model is suitable for the numerical simulation of the operational principle of the SHP, both on a laboratory scale and on a real scale, allowing the investigation of its fluid dynamic behavior.

Abstract: Numerical modelling tools provide valuable means to quantitatively control thermomechanical processing. Several modelling tools have been applied and developed at University of Oulu during previous years, such as finite element models for hot rolling, recrystallization models, heat transfer and conduction model, coupled with phase transformation, as well as cellular automata and phase field models for simulating phase transformation during cooling. This article describes the overall development and recent progress of the developed numerical modeling tools.

Abstract: To prevent arrays of basal plane dislocations (BPD) forming during grown 4H-SiC single crystals, the growth cell in physical vapor transport (PVT) growth was modified by adapting the temperature gradients, the seed attachment method and the seeding phase. The resulting reduction in stress was modeled numerically and the crystals were investigated by X-ray topography (XRT) and molten potassium hydroxide (KOH) etching. Due to these modifications, the formation of BPD arrays was completely suppressed.

Abstract: A finite element model for thermal engineering calculation of fire-resistant multi-hollow reinforced concrete floor in the ANSYS software package has been developed. The model allows to evaluate the fire resistance of fire-resistant and unprotected reinforced concrete structures both under load and without it. With the help of the developed model, the heat engineering calculation of the fire-resistant reinforced concrete multi-hollow slab was carried out. The results of numerical simulation are compared with the results of experimental study of fire resistance. An approach is proposed that allows to take into account all types of heat transfer by specifying cavities as a solid body with an equivalent coefficient of thermal conductivity. The adequacy of the developed model was checked, as a result of which it was established that the calculated values of temperatures correlate satisfactorily with the experimental data. The largest deviation in the measurement of temperatures is observed at 100 minutes of calculation and is about , which is 9%.

Abstract: The study investigates the reduction in masonry walls' strength with different opening sizes and aspect ratios using simplified micro modeling. Calibration of the numerical wall model was done by following an existing wall model from the literature. Springs (COMBIN39) were used to model the compression and shear strength of mortar, whereas contact elements (CONTA178) were used to model the bond between mortar and bricks. The load was provided in two phases; first, the gravity load was applied in the vertical direction to compress the wall then the lateral load was applied. Five walls with an opening size 0%, 1.85%, 3.66%, 10.91%, and 16.5% of the total wall area have been modeled in this study. The analysis results showed that up to an opening area of 4% masonry wall showed approximately 50% reduction in strength and stiffness. Beyond 4% opening size, strength and stiffness drop almost linearly. Such modeling can save cost, time, and know beforehand the type of failure of a masonry wall to avoid life loss.

Abstract: Sandy soil formations are widespread around the globe, particularly in the Arabian Peninsula. The Sandy formations were created as a result of long-term geological activities including but not limited to alluvial and wind deposition. Since the alluvial deposits contain fine soils, the clay layers are often intercepted in the foundation supporting strata. The geotechnical foundation design based on field and lab investigations usually relies on the average response of the layered strata and can satisfy both shear and settlement criteria. However, the enduring sustainability of the heavily loaded foundations is required to be investigated in detail. In this study FEM based numerical investigations have been carried out on a thin raft foundation resting on granular soil, with a soft clay layer in the influence zone. The COMSOL Multi-physics platform has been used for the analysis. The study cases are planned based on the thickness of the clay layer and building load. The analysis results predict the risk involved in the sustainability of rafts in terms of the settlement. The field engineers and designers are recommended to consider the risk and plan accordingly