Number Of Meshes Research Articles

Simplification and unfolding of 3D mesh models: review and evaluation of existing tools

Generation of planar patterns from 3D shapes is required in many fields such as design of airplane wings, car bodies, shoes and textile products. Unfolding and folding processes are common methods to form a 3D shape from 2D surfaces. A 3D mesh surface is segmented in unfolding process to form 2D patches without overlapping. The patches are then used as patterns for cutting materials to fold them back into the 3D shape. A mesh surface can be very complex with a large number of triangles. It is often required to simplify meshes with some preserved geometrical details before the generation of planar patterns for unfolding. This paper reviews and evaluates existing software tools for both mesh simplification and unfolding of 3D shapes. Performance is evaluated for different simplification algorithms implemented in software tools such as Meshlab and Instant-Meshes. The optimal number of meshes is searched for the minimal error. The algorithms are evaluated based on the efficiency and accuracy of the simplified model. Hausdorff Distance measurement is used for the accuracy assessment. The study presents a comprehensive comparison of three different software tools in unfolding for generation of a set of 2D patches from 3D models. The software tools, Pepakura Designer, Blender and SketchUp, are compared in terms of functionalities and performances in the execution time, automation, number of generated 2D patches and editing tools. Case studies are conducted to illustrate the evaluation in both mesh simplifications and unfolding procedures.

Experimental and transient thermal analysis of screen mesh wick heat pipe

Transient thermal analysis of a screen mesh wick heat pipe is performed with a screen mesh numbers 60 and 100 using de-ionized water as working fluid, which is applicable in electronics cooling. Based on evaporation and condensation phenomenon heat pipe is operating. Experiments are conducted (ranging from 20Watts-160Watts) with different inclination angles (15,30,60,90) for calculation of thermal resistance(Rth) and heat transfer coefficient (h), at different mass flow rates and heat inputs. Computational transient thermal analysis is done for the same heat inputs using ANSYS 16.0. It is observed that thermal resistance decreases with increase in heat input [maximum at 0.042(°C//W), minimum at 0.023 (°C/W)] because fluid molecular bonding decreases with increase in heat input. Heat transfer coefficient values are maximum at 8800 (W/m2K) for transient thermal analysis and 8500 (W/m2K) for experimental. The Heat transfer coefficient is more in thermal analysis when compared to experimental results because heat loss is less in ANSYS and more in practical. At 60 W of heat input the maximum Heat transfer coefficient is found.

Observation of Spirulina platensis cultivation in a prototype household bubble column photobioreactor during 107 days

Fresh Spirulina is more favorable than dried one, yet its ease of deterioration necessitates production of biomass that can be immediately consumed. We developed a prototype household photobioreactor and studied the semi-continuous cultivation and harvest conditions within 107 days. Three growth phases were observed featuring different growth rate and recovering time after harvest. Nutrients were consumed at rates of Fe > N > P > Mg > K. The pH mounted rapidly when below 9 and varied slowly between 9 and 10, whose variation positively correlated with that of biomass concentration. Bacterial load was at a constant level of about 2 × 104 CFU, indicating good sanitary condition. Harvesting efficiency improved with greater biomass and filtration sack mesh number until reaching 3.5 g·L−1 and 200, respectively. We hope this study can help the method development of fresh Spirulina cultivation in miniaturized systems.

Nonlinear free convection flow of micropolar nanofluid over a cylinder

AbstractBuoyancy‐determined steady, laminar nonlinear convection flow of micropolar nanofluid with Soret effect, viscous dissipation over a cylinder were evaluated numerically using method bvp4c from matlab software for assorted quantities of leading parameters. Mathematical modeling for the flow problem has been completed with fitting resemblance change and dimensionless variable. A variable similarity solution is offered that bases on various quantities of leading parameters. Influences of these parameters on , are tested and displayed with the charts and graphs. The convergence test has been continued; for quantity of spots larger than suitable mesh number of points. The correctness is unchanged, but it takes time. Also, a comparison with prior study reachable in the literature has been offered with very good conformity is got. The findings show that the existence of Soret number agrees to enhance concentration profile , Wall couple stress coefficient and Nusselt number . But the presence of Eckert Number Ec, allows declining velocity, microrotation, temperature, and concentration profiles.

Removal of Cadmium from Simulated Wastewaters Using a Fixed Bed Bio-electrochemical Reactor

In this research, the removal of cadmium (Cd) from simulated wastewater was investigated by using a fixed bed bio-electrochemical reactor. The effects of the main controlling factors on the performance of the removal process such as applied cell voltage, initial Cd concentration, pH of the catholyte, and the mesh number of the cathode were investigated. The results showed that the applied cell voltage had the main impact on the removal efficiency of cadmium where increasing the applied voltage led to higher removal efficiency. Meanwhile increasing the applied voltage was found to be given lower current efficiency and higher energy consumption. No significant effect of initial Cd concentration on the removal efficiency of cadmium but increasing the initial concentration would be given higher current efficiency and lower energy consumption. The results established that using a pH value lower than three results in a sharp decrease in the removal efficiency as well as using a pH value higher than seven results in decreasing the removal efficiency. Using a mesh number higher than 30 gave a lower removal efficiency. The best operating conditions were found to be an applied potential of 1.8 V, an initial Cd concentration of 125 ppm, and a pH of 7. Under these operating conditions with the using a stack of stainless with mesh number 30 as a packed bed cathode, a complete removal efficiency of Cd(100%) was obtained at a current efficiency of 83.57% and energy consumption of 0.57 kWh/kg Cd.

Method of Adhesion Cell Segmentation Based on Mathematical Morphology in the Preparation of Micro Nanowood Powder

As a new type of environmental protection material, micro nanowood powder has a great relationship with mesh number and wood species, and the premise of wood property recognition is accurate extraction of cell parameters. Adhesion often exists in the cell images of coniferous wood, and the right segmentation of adhesion cells constitutes the prerequisite to ensure the accuracy of the identification of species. In this paper, we have put forward a method based on mathematical morphology for the segmentation of adherent cells, and we have compared the method with that of parallel cells and series cells respectively. As shown by the experimental results, the method proposed in this study proves to be effective for two ordinary adherent cells thanks to its optimal stability and robustness.

Reduced search space combined with particle swarm optimization for distribution system reconfiguration

This paper presents a methodology based on a mesh analysis technique to reduce the search space of the distribution system reconfiguration problem. After reducing the search space, the metaheuristic particle swarm optimization (PSO) was used to solve the problem, finding the best values presented in the literature. In the proposed methodology, the subsets of candidate switches were initially established through a two-stage heuristics. In the first stage, the number of open switches required to keep the radial configuration was calculated, which is the number of meshes on the system, and in the sequence the switches that make up each mesh were identified. In each subset, only one switch is opened, which makes the search process more efficient, compared to the analysis using all the switches. In the second stage of heuristic, the number of switches of the subsets was decreased with the help of an optimal power flow (OPF), which determines the switches from the subsets of first stage more propitious to be opened, this being the main contribution of the work. The PSO was developed for minimizing power losses in the distribution network lines subject to the following constraints: (a) minimum and maximum voltage limits; (b) radial network topology; and (c) balance of active and reactive power in the network buses. The algorithm was validated in four radial distribution systems: 5 nodes with 7 lines, 16 nodes with 21 lines, 33 nodes with 37 lines and 70 nodes with 74 lines.

Mechanistic modeling and numerical simulation of axial flow catalytic reactor for naphtha reforming unit.

Naphtha catalytic reforming (NCR) process has been of tremendous attention all over the world owing to the significant requirement for high-quality gasoline. Industrialized naphtha reforming unit at oil refineries applies a series of fixed bed reactors (FBRs) to improve the quality of the low-octane hydrocarbons and convert them to more valuable products. The prominent purpose of this research is to understand the catalytic reactor of naphtha reforming unit. For this aim, an appropriate mechanistic modeling and its related CFD-based computational simulation is presented to predict the behavior of the system when the reactors are of the axial flow type. Also, the triangular meshing technique (TMT) is performed in this paper due to its brilliant ability to analyze the results of model’s predictions along with improving the computational accuracy. Additionally, mesh independence analysis is done to find the optimum number of meshes needed for reaching the results convergence. Moreover, suitable kinetic and thermodynamic equations are derived based on Smith model to describe the NCR process. The results proved that the proceeding of NCR process inside the reactor significantly increased the concentration amount of aromatic materials, lighter ends and hydrogen, while deteriorated the concentration amount of naphthene and paraffin. Moreover, the pressure drop along the reactor length was achieved very low, which can be considered as one of the momentous advantages of NCR process.

A novel three-dimensional numerical model for PV/T water system in hot climate region

Hybrid PV/Thermal systems (PV/T) are proposed to harvest the two renewable forms of solar energy, electrical and thermal. The use of PV/T systems improves electrical efficiency while utilizing the available solar thermal energy for various heating applications. In this work, numerical simulations perform for PV/T system in hot climate conditions. The cooling system consists of eleven channels arranged in parallel to each other on the backside of the PV module. A novel three-dimensional numerical model of the PV/T system was developed to evaluate the thermal efficiency. The standard k – epsilon model was used to simulate the flow. This novel system was based on using symmetric-convection boundary conditions for the right and left sides of the PV/T model and symmetric-symmetric boundary conditions for the middle cooling channels rather than simulating the whole cooling system. Using one channel simulation allows the creation of less number of meshes, hence, reduces the computational time. The thermal efficiency was estimated by the superposition method for all cooling channels of the PV/T system. The thermal efficiency of the PV/T system was 60% at 0.4 (L/min) and 68% at 5.4 (L/min). The obtained results were in good agreement with the results presented in the literature.

The water stability research of the rubber powder-modified asphalt mixture

In recent years, research shows that crumb rubber modified asphalt can not only improve the pavement performance, but also reduce the pollution of waste tires. Therefore, based on the freeze-thaw test, the influence of hydrogen peroxide, rubber powder mesh number and rubber powder content on the stability of rubber modified asphalt mixture is studied. The results show that when the rubber powder content is 21% and the number of rubber powder mesh is 60, the rubber powder modified asphalt mixture has good stability, and hydrogen peroxide can improve the water stability of rubber powder modified asphalt mixture.

Performance evaluation of soil mixtures treated with graphite and used as barrier fill material for high-level radioactive waste repository

Buffer/backfill material is an important engineering barrier in a deep geological repository of high-level radioactive waste (HLW). Its thermo-hydro-mechanical (THM) performance is very important for the safe and stable operation of the HLW repository system. Natural graphite powder mixed with sodium bentonite forms a buffer/backfill material that can dissipate heat quickly and provide strong isolation. In this paper, the THM characteristics of bentonite–sand–graphite–polypropylene fiber (BSGF) mixtures, used as a buffer/backfill material, were studied through a series of laboratory tests. The influence of graphite and polypropylene fiber contents on thermal conductivity, swelling pressure, hydraulic conductivity, and strength properties of BSGF mixtures with different sand contents was analyzed. Experimental results indicated that the graphite content, the maximum graphite mesh number, and the initial dry density of bentonite–graphite mixtures influenced the thermal conductivity of bentonite–graphite mixtures. The addition of polypropylene fiber was found to enhance the shear strength and inhibit cracking without significantly affecting the expansivity, permeability, and thermal conductivity of the BSGF mixtures. This study provides a new buffer/backfill material that can improve the stability, functionality, and thermal efficiency of the HLW repository.

Unsteady 2D and 3D Navier-Stokes Solver with Application of Multigrid Scheme to Pressure Poisson Fractional Step on Arbitrary Unstructured Grids in Various Applications with Emphasis on Ship Motion

A 3D unsteady computer solver is presented to compute incompressible Navier-Stokes equations combined with the volume of fraction (VOF) method on an arbitrary unstructured domain. This is done to simulate fluid flows in various applications, especially around a marine vessel. The Navier-Stokes solver is based on the fractional steps method coupled with a finite volume scheme and collocated grids by which velocity components and pressure fields are defined at the center of the control volume. However, the fluxes are defined at the midpoint on their corresponding cell faces. On the other hand, the CICSAM (Compressive Interface Capturing Scheme for Arbitrary Meshes) scheme is applied to capture the free surface. In the presented fractional step method, the pressure Poisson equation suffers from poor convergence rate by simple iterative methods like Successive Overrelaxation (SOR), especially in simulating complex geometrics like a ship with appendages. Therefore, to accelerate the convergence rate, an agglomeration multigrid method is applied on arbitrary moving mesh for solving pressure Poisson equation with two well-known cycles, V and W. In order to maintain accuracy, the geometry details should not change in grid coarsening procedure. Therefore, the boundary faces are assumed to be fixed in all grids level. This assumption requires nonstandard cells in coarsening procedures. To investigate the performance of the applied algorithm, various flows including one and two-phase flows are studied in two and three dimensions. It is found that the multigrid method can speed up the convergence rate of fractional step twofold. In most cases (not all), W cycle displays better performance. It is also concluded that the efficiency of the cycle depends on the number of meshes and complexity of the problem and this is mainly due to the data transferring between grids. Therefore, the type of cycle should be selected judiciously and carefully, while considering the mesh size and flow properties.

A new holder/container with a porous cover for atomic layer deposition on particles, with transport analysis and detailed characterization of the resulting materials

Atomic layer deposition (ALD) is widely used in the semiconductor and materials industries for depositing thin films. Here, we describe a holder/container for performing ALD on particles that does not require agitation. This device contains a broad, shallow, circular recess that holds the particles. Two different frits and combinations of stacked meshes were explored as a cover to this holder to restrict the movement of the particles while still allowing good conductance of the ALD reagent gases. A mathematical discussion of the diffusion through the frits and stacked meshes is presented. As confirmed by spectroscopic ellipsometry (SE) on planar witness silicon shards, consistent, high‐quality film growth took place inside and outside the holder. The performance of the holder was demonstrated with ~5‐μm zirconia particles that were coated with alumina from trimethylaluminum (TMA) and water, and with zinc oxide from diethylzinc (DEZ) and water. Deposition on different amounts of particles was investigated (50, 100, 200, and 500 mg). Parasitic chemical vapor deposition (CVD) appeared to be present when a greater number of particles or meshes were used. ALD coating on particles was also confirmed by X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and energy‐dispersive X‐ray spectroscopy (EDS).

Multifunctional Electromagnetic Interference Shielding Ternary Alloy (Ni-W-P) Decorated Fabric with Wide-Operating-Range Joule Heating Performances.

Flexible electromagnetic interference (EMI) shielding textiles with wide-operating-range Joule heating performances are urgently indispensable in the application of artificial intelligence, communication industry, and wearable electronics. Herein, a simple and cost-effective approach is proposed to construct multifunctional textiles by electroless depositing a nickel-tungsten-phosphorus (Ni-W-P) ternary alloy on a polyamide (PA) fabric. The resultant fabric with a thickness of ∼117 μm exhibits a favorable EMI shielding effectiveness (SE) of 43.6 dB within 2-12.5 GHz. Particularly, finite difference time domain (FDTD) simulation was introduced to investigate the effects of the PA fabric mesh number and Ni-W ratio on the EMI SE value, which was validated by experimental results. In addition, the conductive fabric demonstrates excellent heating efficiency (up to 140 °C under 2 V within 60 s), a wide operating range (from 40 to 140 °C), and simultaneously, satisfactory reproducibility by undergoing dozens of heating and cooling cycles. Notably, EMI SE of the multifunctional fabric remains unchanged even after a series of durability measurements including 180 °C heating, ultrasonication treatment, and repetitive peeling tests, respectively. Therefore, the prepared Ni-W-P coated PA fabric with prominent chemical stability and mechanical robustness endows enormous potential in multi-scene applications.

Effect of mesh on CFD aerodynamic performances of a container ship

In this paper, a commercial CFD code, ANSYS-Fluent has been used to investigate the effect of mesh number generated in the computed domain on the CFD aerodynamic performances of a container ship. A full-scale model of the 1200TEU container ship has been chosen as a reference model in the computation. Five different mesh numbers for the same dimension domain have been used and the CFD aerodynamic performances of the above water surface hull of the ship have been shown. The obtained CFD results show a remarkable effect of mesh number on aerodynamic performances of the ship and the mesh convergence has been found. The study is an evidence to prove that the mesh number has affected the CFD results in general and the accuracy of the CFD aerodynamic performances in particular.

A Comparative CFD Study of Side-view Mirror and Side-view Camera Usages on a City Bus

In this study, the effects of classical side mirrors and side-view cameras on the aerodynamic drag coefficient of a city bus model were investigated with Computational Fluid Dynamics (CFD). The surface profile of 1/5 scale bus was modeled with CATIA v5 program. Aerodynamic analyzes were per-formed with ANSYS Fluent® v18. Reynolds Average Navier-Stokes (RANS)-based Reynolds Stress Model (RSM) was used as the turbulence model. The ground effect was taken into consideration in all analyzes. The solution do-main for 5% blockage ratio was created. Inflation layers are used on the ve-hicle surface regarding velocity changes due to viscous effects. The mesh number independence of analyzes was examined for the bus model without side mirrors and provided for 1.3 M mesh element. The Reynolds number in-dependence of the analysis was investigated by using the optimum number of mesh. Free flow velocity of 90 m/s and above were found to be adequate for Reynolds number independence. The drag coefficient was calculated for the bus with side mirrors by using optimum mesh and wind speed as well. The drag coefficients for the bus with side mirrors and side view cameras were de-termined 0.53 and 0.521 respectively.

Nonmatching Discontinuous Cartesian Grid Algorithm Based on the Multilevel Octree Architecture for Discrete Ordinates Transport Calculation

Obtaining sufficiently accurate geometric descriptions is a crucial prerequisite for reliable particle transport calculations. Conventional transport algorithms on Cartesian grids use a highly efficient sweep technique and numerous mature discretization methods despite their modeling deficiency for complex geometries. To achieve a more accurate geometric description, a cell-based nonmatching Cartesian grid algorithm is proposed on the basis of the multilevel octree architecture. Transport sweep is performed according to the tree branch relationship of nested mesh distributions. The angular flux transmission between discontinuous grids is handled by the flux spatial moment mapping technique, and multiple zero-order mapping schemes are developed, including finite element interpolation, distance interpolation, and exponential fitting methods for treating upwind flux distributions of different relative shapes. The first-order mapping schemes are modified and improved for linear and exponential short characteristic discretization methods. The mapping accuracy is evaluated for polynomial and exponential functions, and a new spatial shape factor is presented for measuring the degree of nonlinearity. The multilevel octree grid (MLTG) algorithm is tested for neutron transport benchmarks, and good agreement with Monte Carlo and standard SN results is achieved. The number of meshes in the VVER shielding model is reduced from 18 million to 2 million using 3-level octree grids with the same geometric description accuracy. Numerical verification of a one-group fixed-source problem shows that 4-level and 5-level MLTG results with proper spatial discretization schemes can achieve relative deviations of less than 3% and 5% for detector region flux, respectively.

Experimental study on the behavior of carbon-fabric reinforced cementitious matrix composites in impressed current cathodic protection

This paper presents experimental investigations on the tensile and flexural behavior of Carbon-Fabric Reinforced Cementitious Matrix (C-FRCM) composites in Impressed Current Cathodic Protection (ICCP). A total of eighteen C-FRCM composites are fabricated and tested. The effects of the current density in ICCP and the ply number of carbon fabric (CF) mesh on the mechanical properties of C-FRCM composites are studied. In the tensile tests, a digital image correlation (DIC) system is employed to capture the strain evolution of C-FRCM composites during the loading process. The parameters of the stress-strain relationships of C-FRCM composites are determined from the experimental results. In the bending tests, the load-central deflection relationship of the specimens is presented. It is found that the current density has detrimental effects on both ultimate bearing capacity and ductility of C-FRCM composites. In the ICCP procedure, increasing the ply number of CF mesh is an effective way to increase the safety margin of C-FRCM composites to resist the external force.

MHD nonlinear natural convection flow of a micropolar nanofluid past a nonisothermal rotating disk

AbstractThe aim of this analysis is to examine the steady, laminar boundary layer flow of a micropolar nanofluid owing to a rotating disk in the presence of a magnetic field and thermal and solutal nonlinear convection and nonisothermal parameters. The governing joined partial differential equations are converted into nonlinear ordinary differential equations by means of available transformations. The equations are calculated using the method bvp4c from Matlab software. The convergence test has been maintained; for the number of spots greater than the appropriate mesh number of points, the precision is not influenced, but the set time is boosted. Moreover, various quantities of the main parameters on skin friction coefficients, wall couple stress coefficients, Nusselt number, Sherwood number, velocities, temperature, and concentration of nanofluid are analyzed by means of tables and graphs. The results indicate that the presence of the nonisothermal parameter boosts the radial skin friction, temperature, and Sherwood number but causes decaying concentration distributions, the azimuthal skin friction coefficient, and Nusselt number that indicate the diffusion of momentum occurs more around the surface of the rotating disk.

Experimental study on high-temperature stability of rubber powder-modified Asphalt mixture

Waste rubber powder-modified asphalt can not only improve the asphalt pavement performance but can also solve the environmental pollution problem caused by waste tires. In this paper, through rutting tests, the effects of three different factors, the rubber powder content, rubber powder mesh number, and hydrogen peroxide content, on high-temperature stability of the mixture are systematically studied. The results reveal that the optimum rubber powder mesh is 60 mesh and the best rubber powder content is 21% for high-temperature stability of a rubber-modified asphalt mixture. At the same time, hydrogen peroxide can improve the high-temperature stability of the asphalt mixture.