1. Settling of mesoplastics in an open-channel flowLuka Kevorkijan, Elvis Žic, Luka Lešnik, Ignacijo Biluš, 2022, izvirni znanstveni članek Opis: Pollution of water by plastic contaminants has received increasing attention, owing to
its negative effects on ecosystems. Small plastic particles propagate in water and can travel long
distances from the source of pollution. In order to research the settling motion of particles in
water flow, a small-scale experiment was conducted, whereby spherical plastic particles of varying
diameters were released in an open-channel flow. Three approaches were investigated to numerically
simulate the motion of particles. The numerical simulation results were compared and validated
with experimental data. The presented methods allow for deeper insight into particle motion in
fluid flow and could be extended to a larger scale to predict the propagation of mesoplastics in
natural environments.
Ključne besede: dense discrete phase model, discrete element method, diameter, discrete phase model, mesoplastics, particles, settling
Objavljeno v DKUM: 20.03.2025; Ogledov: 0; Prenosov: 0
 Celotno besedilo (3,51 MB)
Gradivo ima več datotek! Več... |
2. Wear simulation of the conveyor belt transfer chute using the DEMTone Lerher, Žan Grum, Marko Motaln, Matej Zadravec, 2024, izvirni znanstveni članek Opis: This paper presents a wear simulation-based performance evaluation of the conveyor belt transfer chute using the DEM (Discrete Element Method). Compared to known analytical and empirical wear models, DEM simulation can significantly increase the performance of wear analysis by enabling the analysis and optimization of highly complex geometries of material handling systems such as conveyor belt transfer chutes. Only the correct design of the conveyor belt transfer chute has the potential to significantly extend its service life, resulting in considerable cost savings. Based on the parametric analysis of different angles and radius in the upper head and lower section of the transfer chute, a new geometry of the transfer chute was proposed. The wear depth of the new conveyor belt transfer chute is compared with the wear resistant and low-carbon steel of the transfer chute along with the moderate and relatively high values of the solid granules mass flow. The results show that the wear depth of the transfer chute can be significantly reduced by using the wear-resistant steel compared to the low-carbon steel, which is significantly evident in high throughput rates of the solid granules mass flow.
Ključne besede: bulk material flow, Discrete Element Method (DEM), transfer chute wear simulation, archard and relative wear, performance analysis
Objavljeno v DKUM: 10.03.2025; Ogledov: 0; Prenosov: 5
Celotno besedilo (544,47 KB)
Gradivo ima več datotek! Več... |
3. Innovative approaches to wear reduction in horizontal powder screw conveyors : a design of experiments-guided numerical studyMarko Motaln, Tone Lerher, 2024, izvirni znanstveni članek Opis: Numerical simulations play a vital role in the modern engineering industry, especially when faced with interconnected challenges such as particle interactions and the structural integrity of conveyor systems. This article focuses on the handling of materials and emphasizes the importance of using parametric numerical analysis to improve efficiency, reduce wear, and enhance the structural integrity of horizontal screw conveyors. Through the utilization of the Design of Experiments, we systematically investigated critical parameters such as screw pitch, clearance, wear, rotational velocity, and additional structural factors. This examination was carried out within a well-defined parametric framework, utilizing a combination of software tools provided by the Ansys suite and Minitab. The findings demonstrate the effectiveness of the Design of Experiments analysis in achieving improved performance and provide valuable insights for engineers and researchers involved in the design of conveyor systems. Furthermore, this comprehensive approach clarifies how conveyor systems respond to changes in parameters and highlights the complex interaction between transported particles and the conveyor system. We present a detailed analysis that clarifies the complex relationships and dependencies among different parameters, providing engineers and researchers with valuable insights. By understanding the interactions of these factors, the methodology provides not only results but also a strategic framework for advancing conveyor system design and engineering practices.
Ključne besede: discrete element method, design optimization, horizontal screw conveyors, parametric study, conveying equipment, bulk handling, bulk solids, abrasive wear, screw conveyor, FEA, performance analysis
Objavljeno v DKUM: 09.04.2024; Ogledov: 275; Prenosov: 48
Celotno besedilo (10,51 MB)
Gradivo ima več datotek! Več... |
4. |
5. Reconstruction of a fluid bed device for separating granular material from the grinding process of rapid antigen testsMiha Jordan, Tilen Švarc, Peter Majerič, Rebeka Rudolf, Matej Zadravec, 2023, izvirni znanstveni članek Opis: The article includes the study and reconstruction of a fluid bed device with the purpose of separating the granular material from the grinding process of rapid antigen tests. The following techniques were performed, with the purpose of characterisation of the ground particles: sieve analysis, X-ray fluorescence spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. The paper includes experimental testing of a simplified separation process with zeolite spheres and paper strips, supported by a numerical model. The flow conditions’ impact on the behaviour and interactions of particles of the considered problem were simulated using coupled computational fluid dynamics (CFD) and the discrete element method (DEM) approach. The separation process of zeolite spheres and paper strips was found to be efficient. The simulation results showed the appropriate behaviour of the particles during the process. We explained the results’ deviations, and we also presented the shortcomings and possible improvements. Further research is required to define the adequacy of the process, while using actual ground material of rapid antigen tests.
Ključne besede: rapid antigen tests, nanomaterials, fluidised bed, computational fluid dynamics, discrete element method, characterisation
Objavljeno v DKUM: 05.01.2024; Ogledov: 378; Prenosov: 54
Celotno besedilo (4,21 MB)
Gradivo ima več datotek! Več... |
6. Numerical simulation of conveying fine powders in a screw conveyor using the discrete element methodMarko Motaln, Tone Lerher, 2023, izvirni znanstveni članek Opis: Due to their high efficiency and spatial utilization, screw conveyors are widely used in pharmacy, agriculture, and industry. Recently, this has made it a popular research subject in the numerical modelling of the transport of bulk solids. Modelling of granular systems at the level of individual particles is mainly possible due to the use of discrete numerical methods. The most common is the use of the Discrete Element Method (DEM), which is still limited from the point of view of simulations on an industrial scale, as increasing the size of the system also increases the cost of simulation. Certain powders with low density, large angles of repose, poor fluidity, and bad flowability can accumulate during transportation, causing inaccurate and non-uniform movement. Additionally, the friction and impact between the particles can cause wear. To address these issues, the present study utilizes the discrete element method to simulate and analyse powder transportation in an inclined screw conveyor using the commercial software ANSYS-ROCKY. Numerous phenomena that arise while transporting and feeding small-sized or irregularly shaped particles, often present in industrial processes, remain insufficiently investigated. This paper aims to analyse the transportation process of adhesive powders in a screw conveyor, with a focus on evaluating the impact of different screw blade speeds on transport. Multiple simulations were conducted, along with the implementation of an additional wear model, to better understand the transport phenomena and wear. An example was used to demonstrate the impact of screw speed on the wear of the transporter due to the interaction between the material and the structure of the conveyor, power consumption, and performance.
Ključne besede: abrasive wear, bulk handling, coarse graining, conveying equipment, discrete element method, screw conveyor
Objavljeno v DKUM: 12.09.2023; Ogledov: 457; Prenosov: 70
Celotno besedilo (1,69 MB)
Gradivo ima več datotek! Več... |
7. Influence of the virtual strain rate of noncohesive granular media on the discrete element methodKiichi Suzuki, 2015, izvirni znanstveni članek Opis: The discrete element method (DEM) is an alternative computational tool for augmenting laboratory experiments because of its advantages in detailing macro- and micro-mechanical information. However, it should be noted that the DEM does not usually consider the convergence for each time step, because of the necessity for a huge calculation time. In that case, it indicates that the uniqueness of the solution is not guaranteed, except in the case of a very small strain rate, even though the behavior looks qualitatively reasonable. At first, the influence of strain rate among numerically imaginary input parameters for a non-cohesive material was investigated for monotonic, biaxial shear tests. Then, new findings were obtained from the DEM simulations. Strain rate has a significant influence on the shear behavior, especially after the peak strength of dense specimens. A quasi-static steady state exists, not a static steady state. The “strong” fabric ratio is closely related to the stress ratio. The maximum slip coordination number occurs around the phase-transformation ratio and the shear band appears around the peak strength.
Ključne besede: discrete element method, DEM, induced anisotropy, quasi-static steady state, strain rate, uniqueness
Objavljeno v DKUM: 14.06.2018; Ogledov: 1144; Prenosov: 227
Celotno besedilo (690,97 KB)
Gradivo ima več datotek! Več... |
8. Numerical simulation of dilute particle laden flows by wavelet BEM-FEMJure Ravnik, Leopold Škerget, Matjaž Hriberšek, Zoran Žunič, 2008, izvirni znanstveni članek Opis: A wavelet transform based BEM and FEM numerical scheme was used to simulate laminar viscous flow. The velocity-vorticity formulation of the Navier-Stokes equations was used. The flow simulation algorithm was coupled with a Lagrangian particle tracking scheme for dilute suspensions of massless particles and particles without inertia. The proposed numerical approach was used to simulate flow and particle paths for two test cases: flow over a backward-facing step and flow past a circular cylinder. We present methods of calculating the pressure and stream function field at the end of each time step. The pressure field was used to calculate drag and lift coefficients, which enable qualitative comparison of our results with the benchmark. The stream function enabled the comparison of streamlines and massless particle paths in steady state low Reynolds number value flow fields, and thus provided an estimate on the accuracy of the particle tracking algorithm. Unsteady higher Reynolds number value flows were investigated in terms of particle distributions in vortex streets in the wake of the cylinder and behind the step. Sedimentation of particles without inertia was studied in the flow field behind a backward-facing step at Reynolds number value 5000.
Ključne besede: boundary element method, velocity-vertocity formulation, discrete wavelet transform, Lagrangian particle tracking, backward-facing step, bluff body flow, dilute particle suspension
Objavljeno v DKUM: 01.06.2012; Ogledov: 2231; Prenosov: 101
 Povezava na celotno besedilo |
9. Two-dimensional velocity-vorticity based LES for the solution of natural convection in a differentially heated enclosure by wavelet transform based BEM and FEMJure Ravnik, Leopold Škerget, Matjaž Hriberšek, 2006, izvirni znanstveni članek Opis: A wavelet transform based boundary element method (BEM) numerical scheme is proposed for the solution of the kinematics equation of the velocity-vorticityformulation of Navier-Stokes equations. FEM is used to solve the kinetics equations. The proposed numerical approach is used to perform two-dimensional vorticity transfer based large eddy simulation on grids with 105 nodes. Turbulent natural convection in a differentially heated enclosure of aspect ratio 4 for Rayleigh number values Ra=107-109 is simulated. Unstable boundary layer leads to the formation of eddies in the downstream parts of both vertical walls. At the lowest Rayleigh number value an oscillatory flow regime is observed, while the flow becomes increasingly irregular, non-repeating, unsymmetric and chaotic at higher Rayleigh number values. The transition to turbulence is studied with time series plots, temperature-vorticity phase diagrams and with power spectra. The enclosure is found to be only partially turbulent, what is qualitatively shown with second order statistics-Reynolds stresses, turbulent kinetic energy, turbulent heat fluxes and temperature variance. Heat transfer is studied via the average Nusselt number value, its time series and its relationship to the Rayleigh number value.
Ključne besede: numerical modelling, boundary element method, discrete wavelet transform, large eddy simulation, velocity-vertocity formulation, natural convection
Objavljeno v DKUM: 31.05.2012; Ogledov: 2625; Prenosov: 87
Povezava na celotno besedilo |
