Mesh Generation Research Articles

Exploring wind curtailment effects and economic implications in the growing variable renewable energy penetration

Several countries continue to invest in variable renewable energy (VRE) sources to replace fossil fuels and achieve a nationally determined contribution. Consequently, as the share of VRE generation in each country's power grid increases, its curtailment also increases. Current studies on VRE curtailment are based on a comparative analysis of statistical data collected from different countries. However, only a few studies present detailed results based on historical curtailment data collected from individual wind farms. This study analyzes the curtailment data collected for three wind farms over four years. The duration, curtailed output, and cost per curtailment were determined to be 200 min, 38 MWh, and $3.02k, respectively. Finally, the curtailment loss to wind farms caused by the increasing share of VRE generation in the power grid was estimated. The curtailed output and curtailment cost are estimated to increase by 1.3 GWh and $107.6k, respectively, when the share of VRE in the power grid increases by 1%. These findings can aid in identifying the curtailment experienced by wind farm operators and subsequent potential economic losses. Moreover, they can form the basis for establishing an efficient curtailment cost compensation system.

Simulation analysis of electric vehicle charging station using hybrid sources

This paper described simulation analysis of electric vehicle (EV) charging station using hybrid sources. This paper highlights electric vehicle charging station with photovoltaic panels, batteries, and diesel generator. This study employs a solar, battery, diesel generator set, and grid electric vehicle charging station to provide continuous charging in is landed, grid-linked, and Diesel generator (DG) set connected modes. By utilizing a solar and battery, the charging of battery in electric vehicle application is the primary objective If the storage battery is poor and there is no solar generation, The mode of charging automatically shifted to grid or diesel generator set. Furthermore, the charging station manages the generator voltage and frequency without the need of a mechanical speed governor in conjunction with the storage battery. The demand is nonlinear at unity power factor (UPF). For continuous charging, power used from the grid or the DG set and it is synchronized to the grid/generator voltage by the point of common coupling voltage. To boost charging station operating efficiency, the charging station also performs all power transfer from car to grid, vehicle to house, and vehicle to vehicle.

Lightweight 3-D Convolutional Occupancy Networks for Virtual Object Reconstruction.

The increasing demand for edge devices causes the necessity for recent technologies to be adaptable to nonspecialized hardware. In particular, in the context of augmented, virtual reality, and computer graphics, the 3-D object reconstruction task from a sparse point cloud is highly computationally demanding and for this reason, it is difficult to accomplish on embedded devices. In addition, the majority of earlier works have focused on mesh quality at the expense of speeding up the creation process. In order to find the best balance between time for mesh generation and mesh quality, we aim to tackle the object reconstruction process by developing a lightweight implicit representation. To achieve this goal, we leverage the use of convolutional occupancy networks. We show the effectiveness of the proposed approach through extensive experiments on the ShapeNet dataset using systems with different resources such as GPU, CPU, and an embedded device.

Marching Windows: Scalable Mesh Generation for Volumetric Data With Multiple Materials.

Volumetric data abounds in medical imaging and other fields. With the improved imaging quality and the increased resolution, volumetric datasets are getting so large that the existing tools have become inadequate for processing and analyzing the data. Here we consider the problem of computing tetrahedral meshes to represent large volumetric datasets with labeled multiple materials, which are often encountered in medical imaging or microscopy optical slice tomography. Such tetrahedral meshes are a more compact and expressive geometric representation so are in demand for efficient visualization and simulation of the data, which are impossible if the original large volumetric data are used directly due to the large memory requirement. Existing methods for meshing volumetric data are not scalable for handling large datasets due to their sheer demand on excessively large run-time memory or failure to produce a tet-mesh that preserves the multi-material structure of the original volumetric data. In this article we propose a novel approach, called Marching Windows, that uses a moving window and a disk-swap strategy to reduce the run-time memory footprint, devise a new scheme that guarantees to preserve the topological structure of the original dataset, and adopt an error-guided optimization technique to improve both geometric approximation error and mesh quality. Extensive experiments show that our method is capable of processing very large volumetric datasets beyond the capability of the existing methods and producing tetrahedral meshes of high quality.

HYDRODYNAMIC ASSESSMENT ALONG THE COAST OF TANJUNG SEDELI, MALAYSIA

Tidal influence plays a significant role in coastal hydrodynamics as the impact may lead to coastal erosion. Tanjung Sedeli located on the southern coast of Malaysia is exposed to low tidal issues which disrupts the navigation of local fishermen due to the shallow river mouth in the area. This study presents the hydrodynamic processes along the shoreline of Tanjung Sedeli. BLUEKENUE was used as the pre-processor to create a bathymetry file and perform mesh generation to set up the initial model boundary which functions as input files for numerical study. TELEMAC2D further processes the hydrodynamic data (tides and currents), calibrated, and validated with the measured field data collected between 24th September to 6th October 2020 covering both spring and neap tide conditions. The nature of tides in the area was mainly mixed tides, predominantly semidiurnal tides. Modelled hydrodynamic values show good conformity with field measurements with an error of 1.4% for water level values, 10.6% and 20o for current speed and direction respectively. Water flows north into the estuary during spring tide with maximum velocity is 0.756m/s surrounding the river mouth and Pulau Tagal. Low velocity values were recorded at the left bank of the river (0.028 m/s) and Pulau Tagal (0.085 m/s) during spring tide. This study provides information on current hydrodynamic condition of the study area.

3D meshless modeling of piezoelectric structure based on the radial point interpolation method

Piezoelectric materials find widespread applications in high-precision actuators and sensors. However, the traditional finite element method falls short in meeting the simulation needs of piezoelectric structures due to complexities in mesh generation and precision requirements for accurate simulations. This paper focuses on adapting and generalizing the meshless modeling technique based on the radial point interpolation method to address three-dimensional simulations of piezoelectric structures and accurately model positive and inverse piezoelectric behaviors. The piezoelectric body is discretized into point cloud data, and displacement and potential are approximated by interpolating values through the radial point interpolation method. Subsequently, a 3D meshless model for general piezoelectric structures is formulated based on the principle of minimum potential energy. The influences of key factors on interpolation accuracy and computational cost were discussed. Numerical examples, featuring a 3D piezoelectric bimorph beam as actuators and sensors, validate the efficacy of this extended approach. Results affirm that the three-dimensional meshless method, rooted in the radial point interpolation technique, achieves superior accuracy in predicting piezoelectric behavior compared to the traditional finite element method. This adaptation not only enhances the applicability of meshless modeling but also represents a significant advancement in accurately simulating complex three-dimensional piezoelectric structures.

Physically Informed Deep Learning Technique for Estimating Blood Flow Parameters in Four-Vessel Junction after the Fontan Procedure

This study introduces an innovative approach leveraging physics-informed neural networks (PINNs) for the efficient computation of blood flows at the boundaries of a four-vessel junction formed by a Fontan procedure. The methodology incorporates a 3D mesh generation technique based on the parameterization of the junction’s geometry, coupled with an advanced physically regularized neural network architecture. Synthetic datasets are generated through stationary 3D Navier–Stokes simulations within immobile boundaries, offering a precise alternative to resource-intensive computations. A comparative analysis of standard grid sampling and Latin hypercube sampling data generation methods is conducted, resulting in datasets comprising 1.1×104 and 5×103 samples, respectively. The following two families of feed-forward neural networks (FFNNs) are then compared: the conventional “black-box” approach using mean squared error (MSE) and a physically informed FFNN employing a physically regularized loss function (PRLF), incorporating mass conservation law. The study demonstrates that combining PRLF with Latin hypercube sampling enables the rapid minimization of relative error (RE) when using a smaller dataset, achieving a relative error value of 6% on the test set. This approach offers a viable alternative to resource-intensive simulations, showcasing potential applications in patient-specific 1D network models of hemodynamics.

An automatic mesh generator for coupled 1D–2D hydrodynamic models

Abstract. Two-dimensional (2D), depth-averaged shallow water equation (SWE) models are routinely used to simulate flooding in coastal areas – areas that often include vast networks of channels and flood-control topographic features and/or structures, such as barrier islands and levees. Adequately resolving these features within the confines of a 2D model can be computationally expensive, which has led to coupling 2D simulation tools to less expensive one-dimensional (1D) models. Under certain 1D–2D coupling approaches, this introduces internal constraints that must be considered in the generation of the 2D computational mesh used. In this paper, we further develop an existing automatic unstructured mesh generation tool for SWE models, ADMESH+, to sequentially (i) identify 1D constraints from the raw input data used in the mesh generation process, namely the digital elevation model (DEM) and land–water delineation data; (ii) distribute grid points along these internal constraints, according to feature curvature and user-prescribed minimum grid spacing; and (iii) integrate these internal constraints into the 2D mesh size function and mesh generation processes. The developed techniques, which include a novel approach for determining the so-called medial axis of a polygon, are described in detail and demonstrated on three test cases, including two inland watersheds with vast networks of channels and a complex estuarine system on the Texas, USA, coast.

An adaptive extended finite element based crack propagation analysis method

In this paper, a method of crack propagation analysis based on adaptive extension finite element is proposed. This method combines adaptive mesh reconstruction technology with extended finite element method (XFEM). Firstly, the model of engineering structure is discretized with the help of mesh generation software, and the initial mesh is divided. Secondly, Construction of XFEM model, and the tip of crack strengthening function is introduced to describe the physical field properties of the crack tip. The integral equation is solved to obtain the crack tip parameters. Then, the adaptive mesh reconstruction technology is built to refine the mesh of crack tip area through the error estimation of crack tip. Finally, the SIFs at the crack tip were calculated using the interaction integral, and the path direction of crack growth was determined using the maximum circumferential tensile stress criterion. Thus, the propagation path can be well traced.

An effective higher order finite element computation method for analyzing the eddy current losses in induction motors using subparametric transformations

An enhanced sub-parametric finite element method is presented for analyzing the eddy current losses in induction motors using higher order sub-parametric transformations. The purpose of this study is to construct a very efficient, simple, and exact higher order sub-parametric approach employing a 2D automated mesh generator implemented in JuliaFEM. Alternating current motors are employed in a wide range of industrial and household applications on a frequent basis such as in fans, water heaters, ovens, pumps and many more. High efficiency of the motors is one of the most desirable parameters of these motors. Eddy current losses are predominant in these motors which are responsible for a decline in the efficiency. Consequently, the use of eddy current analysis is vital in evaluating the behaviour of electric devices under various loads. This paper proposes a novel finite element method approach to minimize the 2D eddy current phenomenon by taking the diffusion equation into account. Eddy currents are the primary source of torque in various types of equipment, such as induction motors. In other cases, it is important to analyse the eddy currents to estimate the losses, reactance, and resistance.

Just-in-Time Fluid Flow Simulation on Mobile Devices Using OpenVisFlow and OpenLB

The present state of research in computational fluid dynamics (CFD) is marked by an ongoing process of refining numerical methods and algorithms with the goal of achieving accurate modeling and analysis of fluid flow and heat transfer phenomena. Remarkable progress has been achieved in the domains of turbulence modeling, parallel computing, and mesh generation, resulting in heightened simulation precision when it comes to capturing complex flow behaviors. Nevertheless, CFD faces a significant challenge due to the time and expertise needed for a meticulous simulation setup and intricate numerical techniques. To surmount this challenge, we introduce paint2sim—an innovative mobile application designed to enable on-the-fly 2D fluid simulations using a device’s camera. Seamlessly integrated with OpenLB, a high-performance Lattice Boltzmann-based library, paint2sim offers accurate simulations. The application leverages the capabilities of the Lattice Boltzmann Method (LBM) to model fluid behaviors accurately. Through a symbiotic interaction with the open-source OpenCV library, paint2sim can scan and extract hand-drawn simulation domains, affording the capability for instant simulation and visualization. Notably, paint2sim can also be regarded as a digital twin, facilitating just-in-time representation and analysis of 2D fluid systems. The implications of this technology extend significantly to both fluid dynamics education and industrial applications, effectively lowering barriers and rendering fluid simulations more accessible. Encouragingly, the outcomes of simulations conducted with paint2sim showcase promising qualitative and quantitative results. Overall, paint2sim offers a groundbreaking approach to mobile 2D fluid simulations, providing users with just-in-time visualization and accurate results, while simultaneously serving as a digital twin for fluid systems.

Numerical simulation prediction of critical heat flux for 5 × 5 rod bundle with multiple grid spacers and different cladding materials

The critical heat flux (CHF) is one of the safety standards for core thermal design and is crucial for the normal operation of the reactor. The CHF problem of rod bundles with grid spacers is a hot topic in related research. The successful design of grid spacers can improve channel CHF by affecting the flow of downstream coolant, and this detection analysis can be achieved through numerical simulation methods. In addition, most simulation studies have not considered the solid region of the cladding, so there is little research on the effect of cladding materials on CHF. The role of grid spacers in rod bundle CHF is the focus of this paper, and the influence of cladding materials is another discussion direction. In this paper, following meticulous mesh generation and computational model validation, a study on the CHF of the 5 × 5 rod bundle with multiple grid spacers and different cladding materials is carried out by using CFD software. The verification results indicated that the physical model established in this study can reasonably predict the generation location and critical power value in the 5 × 5 rod bundle with grid spacers. Furthermore, the study identified that the grid spacer exerts a significant influence on coolant flow within the channel, while the weakening of the mixing effect of the grid spacer on the coolant flow is the main factor to lead the boiling crisis upstream of the grid spacer. By comparing the effects of thermal properties of different materials on CHF, it was found that when the thermal conductivity ratio of the two materials is 1.08, CHF is almost identical under the condition of a reference heat flux of 0.1 MW/m2 as a step size. In addition to thermal properties, further attention may be paid to the influence of surface characteristics of materials on CHF in future work.

Simulation and experimental study on contact pressure distribution of contact interface in single and double bolted connection structures

Bolted joints play an important role in aerospace, machinery manufacturing, weapons and other fields, and the contact pressure distribution at the connection interface seriously affects the service performance of the bolts. Contact pressure analysis is an essential basis and reference for structural design, calibration, inspection, and safety monitoring of bolted connection structures. Considering the preload force and frictional contact between the joint components, a block mapping hexahedron mesh generation and finite element modeling method for bolted connections is presented, and the finite element models of single and double bolted structures are constructed. Then, an experimental test platform for measuring contact pressure distribution is constructed. Comparison of finite element analysis results with experimental results for the contact pressure distribution in the single and double-bolted joints; the root mean squared error of contact pressure distribution is less than 5%, which verifies the effectiveness of the finite element models. After that, the models are used to study the contact pressure distribution in single-bolted joints and contact pressure coupling effect of double-bolted joints, and the normal stress distribution features within members and contact pressure distribution contour are revealed for single and double-bolted joint. Finally, the finite element models are adopted to investigate the effects of the clamping length, preload, material properties, hole clearance, and bolt size on contact pressure distribution in single-bolted joints. The coupling effect of contact pressure distribution in double-bolted joints under different preloads and geometric parameters are also examined.

A three-dimensional numerical model for variably saturated groundwater flow using meshless weak-strong form method

Meshless numerical models have attracted much attention due to the circumvention of troublesome mesh generation. Current meshless numerical groundwater (GW) models either focus on only pumping in fully saturated zone or merely simulate variably saturated GW flow without pumping. However, these two components are both essential for a GW model to represent practical real-world conditions. This gap is bridged in this study by developing a three-dimensional model, CCHE3D-GW-Meshless, using the meshless weak-strong form method. The new model code was verified with three representative cases, and good agreement was found with the analytical/numerical solutions in all cases. CCHE3D-GW-Meshless was then applied to a field case of a pumping well near a meandering river located at Shellmound, Mississippi, USA. The hydrological properties of the site were obtained through calibration which yielded a generally good match with observed data considering the incompletely known heterogeneity in aquifer properties, indicating the applicability of the model.

The boundary element method for acoustic transmission with nonconforming grids

Acoustic wave propagation through a homogeneous material embedded in an unbounded medium can be formulated as a boundary integral equation and accurately solved with the boundary element method. The computational efficiency deteriorates at high frequencies due to the increase in mesh size with a fixed number of elements per wavelength and also at high material contrasts due to the ill-conditioning of the linear system. This study presents the design of boundary element methods feasible for nonconforming surface meshes at the material interface. The nonconforming algorithm allows for independent grid generation, improves flexibility, and reduces the degrees of freedom. It works for different boundary integral formulations for Helmholtz transmission problems, operator preconditioning, and coupling with finite element solvers. The extensive numerical benchmarks at canonical configurations and an acoustic foam model confirm the significant improvements in computational efficiency when employing the nonconforming grid coupling in the boundary element method.

General Meshing Modeling and Dynamic Characteristics Analysis of Helical Gear Pair with Tooth Surface Deviation

General Meshing Modeling and Dynamic Characteristics Analysis of Helical Gear Pair with Tooth Surface Deviation

Development and application of a mesh generator intended for unsteady vortex-lattice method simulations of wind turbines and wind farms

Abstract. In the last decades, the unsteady vortex-lattice method (UVLM) has gained a lot of acceptance to study large onshore–offshore wind turbines (WTs). Furthermore, and due to the development of more powerful computers, parallelization strategies, and algorithms like the fast multipole method, it is possible to use vortex-based methods to analyze and simulate wind farms (WFs). However, UVLM-based solvers require structured meshes, which are generally very tedious to build using classical mesh generators, such as those utilized in the context of finite element methods (FEMs). Wind farm meshing is further complicated by the large number of design parameters associated with the wind turbine (coning angle, tilt angle, blade shape, etc.), farm layout, modeling of the terrain topography (for onshore WFs), and modeling of the sea level surface (for offshore WFs), which makes the use of FEM-oriented meshing tools almost inapplicable. In the literature there is a total absence of meshing tools when it comes to building aerodynamic grids of WTs and WFs to be used along with UVLM-based solvers. Therefore, in this work, we present a detailed description of the geometric modeling and computational implementation of an interactive UVLM-oriented mesh generator, named UVLMeshGen, developed entirely in MATLAB® and easily adaptable to GNU OCTAVE, for wind turbines and onshore–offshore wind farms. The meshing tool developed here consists of (i) a geometric processor in charge of designing and discretizing an entire wind farm and (ii) an independent module in charge of computing the kinematics for the entire WF. The output data provided by the UVLMeshGen consist of nodal coordinates and connectivity arrays, making it especially attractive and useful to be used by other flow potential solvers using vortices, sources and sinks, or dipoles/doublets, among others. The work is completed by providing a series of aerodynamic results related to WTs and WFs to show the capabilities of the mesh generator, without going into detailed discussions of wind turbine aerodynamics, which are not the focus of this paper. The meshing tool developed here is freely available under a Creative Commons Attribution 4.0 International License (Roccia, 2023).

SCADA World: An Exploration of the Diversity in Power Grid Networks

Despite a growing interest in understanding the industrial control networks that monitor and control our critical infrastructures (such as the power grid), to date, SCADA networks have been analyzed in isolation from each other. They have been treated as monolithic networks without taking into consideration their differences. In this paper, we analyze real-world data from different parts of a power grid (generation, transmission, distribution, and end-consumer) and show that these industrial networks exhibit a variety of unique behaviors and configurations that have not been documented before. To the best of our knowledge, our study is the first to tackle the analysis of power grid networks at this level. Our results help us dispel several misconceptions proposed by previous work, and we also provide new insights into the differences and types of SCADA networks.

A velocity-based moving mesh virtual element method

We present a velocity-based moving mesh virtual element method for the numerical solution of PDEs involving boundaries which are free to move. The virtual element method is used for computing both the mesh velocity and a conservative Arbitrary Lagrangian-Eulerian solution transfer on general polygonal meshes. The approach extends the linear finite element method to polygonal mesh structures, achieving the same degree of accuracy. In the context of moving meshes, a major advantage of the virtual element approach is the ease with which nodes can be inserted on mesh edges. Demonstrations of node insertion techniques are presented to show that moving polygonal meshes can be simply adapted for situations where a boundary encounters a solid object or another moving boundary, without reduction in degree of accuracy.

An Implicit Adaptive FDTD Mesh Generation Techniquebased on Tetrahedrons

A novel implicit adaptive FDTD mesh generation method based on tetrahedrons is proposed in this paper. According to the vertex coordinates of tetrahedrons which make up an object, non-uniform grid lines are generated first. These grid lines are constrained by the structure of the object and follow three rules mentioned in the paper. The first rule is to find demarcation points of the object and drop grid lines on these points. The second rule is to make sure all mesh sizes are less than one-tenth of the wavelength by adding more grid lines. The last rule is to densify mesh at the fine structure of the object. Then by comparing the positional relationship between center points of Yee cells and tetrahedrons, the object can be discretized by Yee cells. Finally, numerical examples are given to verify the validity and accuracy of this novel method.