Structure-preserving numerical methods for phase-field surfactant models based on the supplemental variable method (SVM)

Prestressed lining with unbonded annular anchors is a new type of lining used in hydraulic pressure tunnels. First, the key points of numerical modeling are analyzed based on the stress characteristics of the lining. Thus, the corresponding modeling methods are proposed: the contact relationship is set to simulate the different constraint effects of surrounding rock on the lining, the equivalent load and solid model are superposed to simulate the changing prestress state of anchors, and the nonlinear distribution of prestress loss is simulated by applying the gradient load in sections. Finally, based on the finite-difference software FLAC3D, the modeling analysis of Xiaolangdi pressure silt-releasing tunnel in an engineering case is conducted to verify the correctness of the modeling method presented in this study. The research shows that the new modeling method has a clear principle, fast modeling, and reliable results, which is of guiding significance to structure design.

Hybrid numerical methods for exponential models of growth

The paper is devoted to the methods of geometric modeling of plane curves given in the natural parameterization. The paper considers numerical modeling methods that make it possible to find the equation of curvature of the desired curve for different cases of the input data. The unknown curvature distribution coefficients of the required curve are determined by solving a system of nonlinear integral equations. Various numerical methods are considered to solve this nonlinear system. The results of computer implementation of the proposed methods for modeling two curvilinear contours with different initial data are presented. For the first curve, the input data are the coordinates of three points, the angles of inclination of the tangents at the extreme points and the linear law of curvature distribution. The second example considers an S-shaped curve with a quadratic law of curvature distributi.

The project Modelling of Interface evolution in advanced Welding (MIntWeld) is a 4-year international research project funded by the European Commission under their FP7 programme. Its main target is to develop a numerical toolbox which can be used to predict the evolution of interfaces during welding. There are various interfaces involving multiple phenomena and different spatial scales, which can be simulated using corresponding numerical modelling methods respectively. The modelling methods include quantum dynamics, molecular dynamics, phase field, phase field crystal, computational fluid dynamics, phase transformation and heat transfer, thermodynamics, continuum mechanics and life and defects prediction. Although each modelling method is based on different physical theories and involves different scales, they are not isolated. Therefore, this project aims to design a common framework which couples each model with the upstream and/or downstream model at the relevant neighbouring length scales. The data exchange framework which underpins the coupling of the models is described, and typical examples addressing the solution to the challenges faced, such as those of data interpolation between one discretisation of the computational domain and another, are discussed. Initial successes from the model-linking efforts of the authors are also presented.

Accurately establishing a 3D digital core model is of great significance in oil and gas production. The physical experiment method and numerical modeling method are common modeling methods. With the development of deep learning technology, a variety of deep learning algorithms have been applied to digital core modeling. The digital core modeling method based on generative adversarial neural networks (GANs) has attracted wide attention due to its good quality and simple generation process. The disadvantage of this method is that the network needs thousands of trainings to achieve acceptable results. For this reason, this paper proposes to use the pretrained GANs for digital core modeling training, which can greatly reduce the number of network training while ensuring the core modeling effect. We can use the presented method to quickly complete the training and use the trained generator model to obtain multiple digital cores. By analyzing the quality of the generated cores from multiple aspects, it is revealed that the properties of the generated cores are in good agreement with the ones of the real core samples. The results indicate the reliability of the pretrained GAN method.

Due to the complex relationship between the current history through an electroexplosive opening switch (EEOS) and the switch impedance, numerical modeling methods are required to understand the dynamic switch and circuit behavior of inductive energy storage systems incorporating EEOSs. A method for numerically modeling a compact pulsed-power system consisting of a high-current source, an inductive energy store, an EEOS, and a resistive load is developed. Previous models of switch resistance are extended to recognize restrike conditions and enable modeling of system operation after restrike. In addition, the model is developed such that either a transformer or an uncoupled inductor can be implemented as the inductive energy storage component. The required circuit equations are derived, and a technique to model the dynamic circuit resistance utilizing the time derivatives of circuit currents is described. Thus, a unique modeling method, which is entirely user definable and compatible with a variety of numerical processing software, is developed. Detailed descriptions of the system under consideration, the modeling method, and modeling constraints are provided. The equations describing the switch resistance and circuit response are derived. An example simulation in which restrike occurs is presented, and modeling results are compared to experimentally measured data.

. Typical forms of localized corrosion include crevice corrosion, pitting, stress corrosion cracking, and intergranular corrosion. 1 Localized corrosion represents the primary corrosion failure mode for passive/corrosion resistant materials. There has been extensive experimental characterization of the dependence of the susceptibility to corrosion on alloy and solution composition, temperature, and other variables. Computational modeling can play an important role in improving the understanding of localized corrosion processes, in particular when it is coupled with experimental research that accurately quantifies the important characteristics that control corrosion rate and resultant morphology. There are many modeling methods that can be applied, with the choice of method driven by the goal of the modeling exercise. Empirical models 2 can be used to predict performance within the parameter space for which they are created. Such models can provide insight into what kinds of processes might be dominating the corrosion process, but further dissection of controlling factors is more difficult. Numerical modeling, in which the concentration, potential, and current distributions are calculated, plays a role in helping to understand controlling factors. There are several numerical methods that have been implemented by corrosion scientists and engineers. Among these, the finite element method (FEM) has been the most widely used to investigate transport phenomena in systems undergoing. The finite element method (FEM) is a numerical technique used to obtain approximate solutions to the differential equations that describe a wide variety of physical phenomena, ranging from electrical and mechanical systems to chemical and fluid flow problems. Generally, FEM establishes credible stability criteria and provides more flexibility (e.g., in handling inhomogeneity and complex geometries) compared to other numerical modeling methods such as the finite difference method (FDM). The finite element approach in corrosion study was introduced in the early 1980s by Alkire, Forrest, and Fu. 3-5 The FEM approach has demonstrated an ability to predict electrochemical parameters such as potential and current distributions for localized corrosion.

Having many advantages instead of classic wire wound technology; planar magnetic components are largely used. Modeling tools are required to help designers for less time consuming conception. Nevertheless, number of adapted modeling solutions is limited by the complexity of such geometries. The determination of appropriate numerical methods for eddy currents modeling and by this way, ac copper losses evaluation is investigate in this paper.

2 - Summary of numerical techniques for nanofluid modeling

Numerical Methods for Grade-Two Fluid Models: Finite-Element Discretizations and Algorithms

Currently, methods of numerical modelling are widely used. They are especially widely used in the design of turbo compressors. For the specific task of designing new flowing parts of a centrifugal compressor, it is not recommended to deviate from the canonical design techniques, but it is preferable to supplement them with numerical methods. This article is devoted to the end two-element stage investigation of a centrifugal compressor with an axial radial impeller; the stage main dimensions were obtained using the method of V.F. Rice. In order to obtain the necessary pressure characteristics and determine the dependence for the absolute velocity non-uniform distribution at the inlet to the axial radial impeller, the flow path main dimensions were optimized using numerical calculation methods. The calculation was performed using the SST turbulence model using computational gas dynamics methods in the ANSYS CFX software environment. Based on the optimization results, five compressor designs and corresponding characteristics were obtained. The absolute velocity distribution nature at the inlet to the centrifugal compressor axial radial impeller for five flow path variants is investigated. Empirical dependences are obtained for the deviation of the absolute velocity at the inlet in the hub section axial radial impeller and the absolute velocity deviation at the shroud from the absolute velocity at the average diameter based on the results of a numerical experiment. Recommendations are made for further absolute velocity distributions investigating at the inlet to the compressor impeller.

Efficient energy-stable numerical methods for phase-field vesicle membrane models with strict volume and surface area constraints

Three-dimensional geological Earth models typically comprise wireframe surfaces of connected triangles that represent geological contacts. In contrast, Earth models used by most current 3D geophysical numerical modeling and inversion methods are built on rectilinear meshes. This is because the mathematics for computing data responses are simpler on rectilinear meshes. In such a model, the relevant physical properties are uniform within each brick-like cell but possibly different from one cell to the next, producing a pixellated representation of the Earth. In principle, arbitrary spatial variations can be represented if a sufficiently fine discretization is used. However, no matter how fine the discretization of the rectilinear mesh, such a mesh is always incompatible with geological models comprising wireframe surfaces. Also, because the computational resources required by 3D numerical modeling and inversion methods increase dramatically as the discretization of a model is refined, it is never really possible to achieve as fine a discretization as one would like. This exacerbates the mismatch between models that comprise wireframe surfaces and those built on rectilinear meshes. To address this incompatibility, we are using unstructured tetrahedral meshes to specify 3D geophysical Earth models. We hope that working with unstructured meshes will facilitate the construction of common Earth models consistent with both the geological and geophysical data available.

Perovskite solar cells (PSCs) have recently become one of the most encouraging thin-film photovoltaic (PV) technologies due to their superb characteristics, such as low-cost and high power conversion efficiency (PCE) and low photon energy lost during the light conversion to electricity. In particular, the planer PSCs have attracted increasing research attention thanks to their advantages, like hysteresis elimination, large-scale production processability, and having a certified PCE of over 26%. However, there are still some challenges to the development of these cells. To optimize and improve the performance of PSCs, the simulation analysis is as essential as the experimental study. This review intensively describes and discusses the numerical modeling, simulation, and optimization methods of direct n–i–p planer PSCs. This paper classifies the reviewed works based on which PSC’s layers are engineered and provides specific comments for each study. In addition, this study reviews other types of planer PSCs, including inverted p–i–n structures and charge transport layer-free configurations. Finally, with a critical outlook on the currently existing challenges and possible development opportunities, helpful research guidelines are proposed for further improvements.

We introduce methods for modelling and simulation of anisotropic poroelastic materials in the frequency domain. Starting from the equations formulated by Biot, in their anisotropic form, we derive two different symmetric weak forms together with the boundary conditions that has to be satisfied. We employ a mixed displacement-pressure formulation and solutions are obtained by applying the finite element method to the proposed weak forms. In order to illustrate the use of the finite element method, we highlight some particular aspects related to simulations where poroelastic materials are involved. These include convergence of the discretised solution and boundary conditions at interfaces between poroelastic materials and solids/fluids. Results are given for some selected application examples of foam and plate combinations as well as a poroelastic foam with embedded inclusions.