Meshing Tool Research Articles

Design and Numerical Analysis of an Annular Combustion Chamber

Designing a combustion chamber for gas turbines is considered both a science and an art. This study presents a comprehensive methodology for designing an annular combustion chamber tailored to the operating conditions of a CFM-56 engine, a widely used high bypass ratio turbofan engine. The design process involved calculating the basic criteria and dimensions for the casing, liner, diffuser, and swirl, followed by an analysis of the cooling sections of the liner. Numerical simulations using NUMECA software and the HEXPRESS meshing tool were conducted to predict the combustion chamber’s behavior and performance, employing the κ-ε turbulence model and the Flamelet combustion model. Methane was used as the fuel, and simulations were performed for three fuel injection angles: axial, 45°, and 60°. Results demonstrate that the combustion chamber is properly dimensioned and achieves complete combustion for all configurations. The pressure ratio is 0.96, exceeding the minimum design criteria. Additionally, the emissions of unburned hydrocarbons are zero, while nitrogen oxides and carbon monoxide levels are below regulatory limits. These findings validate the proposed design methodology, ensuring efficient and environmentally compliant combustion chamber performance.

Digital twinning of cardiac electrophysiology for congenital heart disease.

In recent years, blending mechanistic knowledge with machine learning has had a major impact in digital healthcare. In this work, we introduce a computational pipeline to build certified digital replicas of cardiac electrophysiology in paediatric patients with congenital heart disease. We construct the patient-specific geometry by means of semi-automatic segmentation and meshing tools. We generate a dataset of electrophysiology simulations covering cell-to-organ level model parameters and using rigorous mathematical models based on differential equations. We previously proposed Branched Latent Neural Maps (BLNMs) as an accurate and efficient means to recapitulate complex physical processes in a neural network. Here, we employ BLNMs to encode the parametrized temporal dynamics of in silico 12-lead electrocardiograms (ECGs). BLNMs act as a geometry-specific surrogate model of cardiac function for fast and robust parameter estimation to match clinical ECGs in paediatric patients. Identifiability and trustworthiness of calibrated model parameters are assessed by sensitivity analysis and uncertainty quantification.

Unstructured mesh tools for magnetically confined fusion system simulations

Unstructured mesh tools for magnetically confined fusion system simulations

TÍNH TOÁN MÔ PHỎNG DÒNG CHẢY TRONG BUỒNG ĐỐT ĐỘNG CƠ NHIÊN LIỆU RẮN VỚI THUỐC PHÓNG HỖN HỢP HAI LỚP

This article presents a method of calculating the simulation of flow in solid fuel combustion chamber, which applied to the two-layer mixed solid propellant motor, using simulation software Ansys Fluent. The regression of burning surface of the propellant is simulated using dynamic meshing tool combined with user-defined functions (UDF), written in C++ programming language. The author proposes a method to calculate the average fire rate for mixed solid fuel, thereby simplifying the simulation process and still get results corresponding to the experimental results. The calculation thrust-time curve has a profile similar to the experimental results. The maximum thrust achieved during the steady burning phase is 4.98 kN, the correspoding experimental value is 5.0 kN.

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).

An efficient parameterized simulation framework for 3D scarf-repaired composite laminates

This paper proposes a parameterized simulation framework for predicting the load-bearing capacity of 3D scarf-repaired composite laminates which remarkably reduces the modeling time from several hours to just a few seconds. The specific implementation is demonstrated through a detailed step-by-step explanation. The main contribution lies in: (1) By introducing a reusable geometric partitioning method for composite layers and implementing a partitioning method-based numbering scheme for element and node, the effective management of element and node IDs of elements and nodes in such complex 3D models is greatly facilitated; (2) By ingeniously combining open-source meshing tools and text rewriting techniques, a highly efficient approach has been developed to construct complete models for such structures, showcasing the remarkable potential of these existing techniques in this field. The reliability of the efficient parameterized simulation framework proposed in this study is verified through the comparison between strength values acquired from progressive damage analysis (PDA) and experiment data reported in the existing literature.

NUMERICAL SIMULATION OF TURBULENT FLOW IN A HEAT EXCHANGER EQUIPPED WITH FINS OF DIFFERENT MATERIALS AND GEOMETRIES

The miniaturization of electronic devices causes heat generation in the system. In this scenario, highly effective heat sinks are needed for the electronic devices. The present study focuses on enhancing heat transfer in heat sinks by using pin fins with different geometries (circular, elliptical, triangular, and square), various materials for pin fins (copper, aluminum, magnesium, tungsten, zinc, and steel), and Al<sub>2</sub>O<sub>3</sub>-EG nanofluid. The analysis is carried out by a commercial computational fluid dynamics (CFD) program called Ansys Fluent 14, which was used to numerically solve the governing equations and boundary conditions. The 3D model is subsequently discretized using the ICEM CFD meshing tool. From the analysis, it has been observed that 331.75 W of heat is lost by using copper material in a heat sink, and magnesium recorded 363.7 W of heat loss, whereas aluminum recorded 319.5 W. Moreover, copper is a great material for transferring heat. This means that heat moves quickly through copper and magnesium as they have good thermal conductivity. Elliptical materials conserve materials more than others when the space is limited to one direction. Elliptical shapes record 461.67 W heat loss.

Challenges of high-fidelity virtual reactor for exascale computing and research progress of China Virtual Reactor

The virtual reactor is a sophisticated software system deployed on supercomputers to simulate physics process or predict component behaviors inside real reactors. It highly relies on advanced modeling and coupling methods, high performance computing and advanced verification and validation (V&V) techniques, which is another important method for reactor engineering design and mechanism research besides experiment. With the advent of exascale computer, it becomes mainstream trend to develop full-core high-fidelity simulation research under the help of exascale computing technology. This paper first summarizes the challenges of developing high-fidelity virtual reactor simulation in exascale computing. The challenges of high-fidelity virtual reactor simulation are introduced from four aspects: science-based modeling methods, high-resolution mesh model, scientific numerical methods , and multiphysics and multiscale coupling. Based on the architecture of exascale computer, the challenges of parallel optimization of virtual reactor for exascale computing are introduced. Furthermore, this paper introduces the recent research progress of China Virtual Reactor (CVR), which is about the parallel optimization for Chinese exascale computers and the functional extensions for achieving full-core high-fidelity simulation. The recent research progress of CVR includes multiscale simulation software of materials, fuel performance simulation software, thermal-hydraulic simulation software, full-core high-resolution meshing tool, and optimization of basic sparse operators.

Developing a novel structured mesh generation method based on deep neural networks

In this paper, we develop a novel structured mesh generation method, MeshNet. The core of the proposed method is the introduction of deep neural networks to learn high-quality meshing rules and generate desired meshes. To accomplish this, MeshNet employs a well-designed physics-informed neural network to approximate the potential transformation (mapping) between computational and physical domains. The training process is governed by differential equations, boundary conditions, and a priori data derived from coarse mesh generation, which has been disregarded in previous studies. The automatic subdivision of a given domain into quadrilateral elements is achieved through efficient feed-forward neural prediction. A series of experiments are conducted to investigate the robustness of the proposed method. The results across different cases demonstrate that MeshNet is fast and robust. It outperforms state-of-the-art neural network-based generators and produces meshes of comparable or higher quality compared to expensive traditional meshing methods. Furthermore, the proposed method enables fast varisized mesh generation without re-training. The simplicity and computational efficiency of MeshNet make it a novel meshing tool in the discretization part of simulation software.

Analysis of Blood Flow in Human Brain Vessels for Newtonian and Non-Newtonian Blood Properties

The cerebral artery system can be affected by various diseases such as stroke, carotid stenosis, vertebral stenosis, intracranial stenosis, aneurysms, and vascular malformations. Understanding the blood flow specific to each patient's cerebral arteries can provide crucial information about how these diseases progress and guide potential treatment options. A patient-specific Magnetic Resonance Imaging (MRI) scan of a human brain was utilized to create a 3D model of the arterial system. Blood flow simulations were conducted using the ANSYS (Fluent) R2021 software package. The ICEM meshing tool within the ANSYS software was employed to prepare the models. The velocity rise and pressure drop were observed in the branching of the basilar artery. This can provide valuable patient specific information on various cerebral diseases, and drug delivery cases. The non-Newtonian properties of blood were established by inputting the Power Law parameters into the ANSYS Fluent system. It was observed that the effects of non-Newtonian properties of blood are relatively negligible for the large vessels studied (> 200 um).

A parallel Python-based tool for meshing watershed rivers at continental scale

A major challenge in compound flooding simulation is representing small rivers in the model mesh. A parallel Python-based tool is developed to support the construction of unstructured grids (UGs) at continental scales. The tool is driven by Digital Elevation Model (DEM), ensuring accurate representation of geomorphic features in the resulting mesh. Its first component (pyDEM) extends an existing tool to detect river thalwegs from DEMs. The second component (RiverMapper) uses the thalwegs to generate river ‘arcs’, which can be directly ingested into meshing tools (e.g., the Surface-water Modeling System). The novelty lies in the explicit 2D representation of rivers in both along- and cross-channel directions, making it ideal for accurate, efficient, and high-resolution continental-scale research. The tool is employed to create a UG for a 3D creek-to-ocean model encompassing the US East and Gulf Coasts，and it greatly improves the flow exchange between the watershed and the coastal zone.

P40: Minimal hemolysis and platelet activation with VentriFlo True Pulse Pump, a novel pulsatile extracorporeal blood pump

Objective: Early pre-clinical work with a novel pulsatile extracorporeal blood pump, VentriFlo True Pulse Pump, have demonstrated delivery of the normal, or heart-like, pulsatile flow. Subsequent design modifications have been implemented to enhance the quality of pulse applications across varying stroke volumes and circuit dynamics. The aim of this study was to support the device development with advanced in silico simulation. Methods: Steady state and transient computational fluid dynamic (CFD) models were generated using ANYSYS 17.2 software (ANSYS Inc., Canonsburg, PA) including SpaceClaim, ANSYS meshing, CFX, and CFD-Post tools. The flow velocity and wall shear stress during two different pump cycles (faster and slower) were evaluated to assess the hemolysis and platelet activation in accordance with Hellums’ criteria. The pump cycles were determined with typical VentriFlo pump filling and pumping times (faster: 0.35 sec each, slower 0.63 sec each). Results: The faster cycle exhibited a peak shear stress of 180 Pa and an exposure time of 0.075 sec, while the slower cycle demonstrated a peak shear stress of 110 Pa and an exposure time of 0.05 sec (Figure 1). Both values were below the Hellums’ threshold criteria for hemolysis and platelet activation. Conclusion: The refined VentriFlo pump demonstrated low hemolysis generation and platelet activation in the CFD model. Additional research efforts are ongoing.Figure 1. The wall shear stress and exposure time for two pump cycles, compared with Hellums’ thresholds.

Modeling, Analysis, and Computational Design of Muscle-driven Soft Robots.

Muscle driving is a critical actuation mode of soft or flexible robots and plays a key role in the motion of most animals. Although the system development of soft robots has been extensively investigated, the general kinematic modeling of soft bodies and the design methods used for muscle-driven soft robots (MDSRs) are inadequate. With a focus on homogeneous MDSRs, this article presents a framework for kinematic modeling and computational design. Based on continuum mechanics theory, the mechanical characteristics of soft bodies were first described using a deformation gradient tensor and energy density function. The discretized deformation was then depicted using a triangular meshing tool according to the piecewise linear hypothesis. Deformation models of MDSRs caused by external driving points or internal muscle units were established by the constitutive modeling of hyperelastic materials. The computational design of the MDSR was then addressed based on kinematic models and deformation analysis. Algorithms were proposed to infer the design parameters from the target deformation and to determine the optimal muscles. Several MDSRs were developed, and experiments were conducted to verify the effectiveness of the presented models and design algorithms. The computational and experimental results were compared and evaluated using a quantitative index. The presented framework of deformation modeling and computational design of MDSRs can facilitate the design of soft robots with complex deformations, such as humanoid faces.

Multi-fidelity aerodynamic design and analysis of propellers for a heavy-lift eVTOL

This paper presents a multi-fidelity propeller design and analysis process, and demonstrates it for the preliminary design of a heavy-lift eVTOL vehicle proposed by GKN aerospace, known as Skybus. The multi-fidelity framework integrates tools and results of variable fidelity levels. A global scan of the design space was first carried out at the low-fidelity stage. The low-fidelity output was converted to 3D shapes and grids through an automatic meshing tool, and high-fidelity CFD simulations and gradient-based optimisation were launched to deliver further improved designs. The method was first verified using a benchmark multi-modal test function. The framework was then demonstrated for the propeller design of the Skybus vehicle. Rectangular blade designs with linear twist were first derived through the Blade Element Momentum Theory and used as the input to the low-fidelity stage for simplicity. Upon the baseline design, the low-fidelity stage managed to find an improved shape with 3% reduced power, while the high-fidelity optimisation further reduced the power by 2.2% under the equality thrust constraint. In addition, this work also reports the propeller pitch-RPM performance map tool that has effectively supported the Skybus development through fast performance predictions and operating condition determination. For propellers with both pitch and RPM regulation, the performance map explicitly correlates various performance scopes and to aid optimisation. The multi-fidelity construction of the performance map and demonstrations of its usage are then presented.

MOOSE Reactor Module: An Open-Source Capability for Meshing Nuclear Reactor Geometries

The U.S. Department of Energy (DOE) Nuclear Energy Advanced Modeling and Simulation (NEAMS) program has developed numerous physics solvers utilizing the open-source Multiphysics Object-Oriented Simulation Environment (MOOSE) framework for multiphysics reactor analysis. These solvers require input finite element meshes representing the discretized spatial domain. Typically, reactor analysts turn to licensed tools for the creation of reactor geometry meshes. Recently, open-source functionality has been added to the MOOSE framework to mesh common reactor geometries and improve MOOSE-based nuclear reactor application user workflows. The new functionality is primarily contained in the new Reactor module of MOOSE and includes support for hexagonal pins, assemblies, and cores, extended Cartesian geometry support, options for modeling static and rotating control drums within a hexagonal assembly, core periphery triangulation, and automatic tagging of pin, assembly, plane, and depletion regions for easier post processing of physics results. A set of reactor geometry mesh builder objects further streamlines the construction of hexagonal and Cartesian cores and allows mapping of materials to regions during mesh generation. The meshes produced with the MOOSE Reactor module may be used directly within MOOSE-based applications or exported as Exodus II files for use in other finite element solvers. The tools have been demonstrated and verified using a variety of NEAMS physics solvers on a range of reactor applications, including a sodium-cooled fast reactor core analysis using Griffin, a fast reactor assembly thermal deformation analysis using MOOSE Tensor Mechanics, and a heat pipe–cooled microreactor coupled analysis using Griffin, Bison, and Sockeye. MOOSE’s Reactor module provides significant advantages compared to the use of external meshing tools when analyzing Cartesian and hexagonal reactor lattices using MOOSE-based applications: immediate accessibility (open-source) to the end user, low barrier to entry for new users, speed of mesh generation, volume preservation of meshed fuel pins, and simplification of analysis workflow when used in conjunction with MOOSE-based applications.

Stress Optimization of Vent Holes with Different Shapes Using Efficient Switching Delayed PSO Algorithm

An effective integrated design optimization method is developed to reduce the maximum von Mises stress around vent holes of a high-pressure turbine sealing disk. It mainly includes four different shape designs (circular, elliptical, race-track, and four-arc) for holes, an updated self-developed modelling and meshing tool, an APDL-based strength analysis, and a self-proposed efficient switching delayed particle swarm optimization (SDPSO) algorithm. The main idea of SDPSO is: (1) by evaluating an evolutionary factor and utilizing a probability transition matrix, a non-homogeneous Markov chain is determined and auto-updated in each generation; (2) the evolutionary factor and the Markov chain are used to adaptively select the inertia weight, acceleration coefficients, and delayed information to adjust the particle’s velocity. The performance of SDPSO is evaluated through two benchmark optimization problems with constraints. The results show that SDPSO is superior to two well-known PSO algorithms in optimization capability, numerical robustness, and convergence speed. Furthermore, SDPSO is used for the stress optimization of vent holes with four different shapes. The results show that: (1) SDPSO is suitable and valuable for practical engineering optimization problems with constraints; (2) the developed integrated design optimization method is effective and advanced for reducing the maximum von Mises stress around the vent holes; and (3) the four-arc hole has more tremendous advantages in reducing the maximum von Mises stress, followed by the elliptical hole, the race-track hole, and the circular hole.

3D fluid–structure interaction simulation of an hydrofoil at low Reynolds number

Understanding the interaction between wings and fluids is of great interest in many fields such as aeronautics, wind turbines, civil engineering, naval and industrial domain, among others. To improve our knowledge, scientists have conducted more and more theoretical studies with numerical simulation. Due to the high complexity of the coupled phenomena leading to time-consuming fluid–structure interaction simulations, the overwhelming majority of these studies are restricted to two dimensions. Here, we present the full three-dimensional fluid–structure simulation of a foil in water. A deformable NACA 0015 wing, at 15° angle of attack, undergoes a 1m.s−1 flow in a water tunnel. We handle the simulation with free open-source software: OpenFOAM (fluid), CalculiX (solid) and preCICE (fluid–structure coupling). An implicit coupling is considered. The access to high-performance computing facilities allows us to run a Delayed-Detached-Eddy Simulation (DDES) based on a 15-million-cell mesh resolving the boundary layer on the wing. We also develop a meshing tool based on free software and Python scripts to facilitate the meshing process of wings or any shape in rectilinear geometries (2D and 3D). Then, we manage a thorough numerical investigation of the 3D phenomena involved in this fluid–structure problem. In particular, we reproduce the vortex-induced vibration process and observe the same fundamental frequency for the vortex shedding, the wing displacement oscillation and the lift and drag coefficients. Thus, we evidence that wing oscillatory displacements, of the order of 0.1% of the chord only, significantly affect the behavior of the flow.

BlenderPhotonics: an integrated open-source software environment for three-dimensional meshing and photon simulations in complex tissues.

.Significance: Rapid advances in biophotonics techniques require quantitative, model-based computational approaches to obtain functional and structural information from increasingly complex and multiscaled anatomies. The lack of efficient tools to accurately model tissue structures and subsequently perform quantitative multiphysics modeling greatly impedes the clinical translation of these modalities.Aim: Although the mesh-based Monte Carlo (MMC) method expands our capabilities in simulating complex tissues using tetrahedral meshes, the generation of such domains often requires specialized meshing tools, such as Iso2Mesh. Creating a simplified and intuitive interface for tissue anatomical modeling and optical simulations is essential toward making these advanced modeling techniques broadly accessible to the user community.Approach: We responded to the above challenge by combining the powerful, open-source three-dimensional (3D) modeling software, Blender, with state-of-the-art 3D mesh generation and MC simulation tools, utilizing the interactive graphical user interface in Blender as the front-end to allow users to create complex tissue mesh models and subsequently launch MMC light simulations.Results: Here, we present a tutorial to our Python-based Blender add-on—BlenderPhotonics—to interface with Iso2Mesh and MMC, which allows users to create, configure and refine complex simulation domains and run hardware-accelerated 3D light simulations with only a few clicks. We provide a comprehensive introduction to this tool and walk readers through five examples, ranging from simple shapes to sophisticated realistic tissue models.Conclusions: BlenderPhotonics is user friendly and open source, and it leverages the vastly rich ecosystem of Blender. It wraps advanced modeling capabilities within an easy-to-use and interactive interface. The latest software can be downloaded at http://mcx.space/bp.

A Large-Scale Comparison of Tetrahedral and Hexahedral Elements for Solving Elliptic PDEs with the Finite Element Method

The Finite Element Method (FEM) is widely used to solve discrete Partial Differential Equations (PDEs) in engineering and graphics applications. The popularity of FEM led to the development of a large family of variants, most of which require a tetrahedral or hexahedral mesh to construct the basis. While the theoretical properties of FEM basis (such as convergence rate, stability, etc.) are well understood under specific assumptions on the mesh quality, their practical performance, influenced both by the choice of the basis construction and quality of mesh generation, have not been systematically documented for large collections of automatically meshed 3D geometries. We introduce a set of benchmark problems involving most commonly solved elliptic PDEs, starting from simple cases with an analytical solution, moving to commonly used test problem setups, and using manufactured solutions for thousands of real-world, automatically meshed geometries. For all these cases, we use state-of-the-art meshing tools to create both tetrahedral and hexahedral meshes, and compare the performance of different element types for common elliptic PDEs. The goal of this benchmark is to enable comparison of complete FEM pipelines, from mesh generation to algebraic solver, and exploration of relative impact of different factors on the overall system performance. As a specific application of our geometry and benchmark dataset, we explore the question of relative advantages of unstructured (triangular/ tetrahedral) and structured (quadrilateral/hexahedral) discretizations. We observe that for Lagrange-type elements, while linear tetrahedral elements perform poorly, quadratic tetrahedral elements perform equally well or outperform hexahedral elements for our set of problems and currently available mesh generation algorithms. This observation suggests that for common problems in structural analysis, thermal analysis, and low Reynolds number flows, high-quality results can be obtained with unstructured tetrahedral meshes, which can be created robustly and automatically. We release the description of the benchmark problems, meshes, and reference implementation of our testing infrastructure to enable statistically significant comparisons between different FE methods, which we hope will be helpful in the development of new meshing and FEA techniques.

Cartesian Meshing Spherical Earth (CMSE): A Code Package to Incorporate the Spherical Earth in SPECFEM3D Cartesian Simulations

AbstractThe SPECFEM3D_Cartesian code package is widely used in simulating seismic wave propagation on local and regional scales due to its computational efficiency compared with the one-chunk version of the SPECFEM3D_Globe code. In SPECFEM3D_Cartesian, the built-in meshing tool maps a spherically curved cube to a rectangular cube using the Universal Transverse Mercator projection (UTM). Meanwhile, the geodetic east, north, and up directions are assigned as the local x–y–z directions. This causes coordinate orientation issues in simulating waveform propagation in regions larger than 6° × 6° or near the Earth’s polar regions. In this study, we introduce a new code package, named Cartesian Meshing Spherical Earth (CMSE), that can accurately mesh the 3D geometry of the Earth’s surface under the Cartesian coordinate frame, while retaining the geodetic directions. To benchmark our new package, we calculate the residual amplitude of the CMSE synthetics with respect to the reference synthetics calculated by SPECFEM3D_Globe. In the regional scale simulations with an area of 1300 km × 1300 km, we find a maximum of 5% amplitude residual for the SPECFEM3D_Cartesian synthetics using the mesh generated by the CMSE, much smaller than the maximum amplitude residual of 100% for the synthetics based on its built-in meshing tool. Therefore, our new meshing tool CMSE overcomes the limitations of the internal mesher used by SPECFEM3D_Cartesian and can be used for more accurate waveform simulations in larger regions beyond one UTM zone. Furthermore, CMSE can deal with regions at the south and north poles that cannot be handled by the UTM projection. Although other external code packages can be used to mesh the curvature of the Earth, the advantage of the CMSE code is that it is open-source, easy to use, and fully integrated with SPECFEM3D_Cartesian.