Mesh generation and optimization of ship hull dirty geometry based on multi-constraint advancing front technique

The 2D and 3D fully automatic hp adaptive Finite Element Method (FEM) codes generate a sequence of optimal hp refined meshes delivering exponential convergence rate of the numerical error with respect to the number of degrees of freedom (and CPU time). The optimal meshes are generated by performing a sequence of h or p refinements on the initial mesh. However, generation of optimal meshes in three dimensions is computationally expensive. We propose an algorithm for transferring of generated 2D optimal meshes into 3D meshes. The algorithm allows us to replace expensive 3D generation of optimal hp mesh by relatively inexpensive 2D generation of optimal meshes. The algorithm generates full revolution of the recorded optimal 2D mesh. The algorithm supports generation of either 3D axially symmetric meshes or non-axially symmetric tilted meshes. We apply that algorithm to perform a sequence of 3D DC borehole resistivity measurements simulations.

Mesh generation is one of the most time consuming aspects of computational solutions of problems involving partial differential equations. It is, furthermore, no longer acceptable to compute solutions without proper verification that specified accuracy criteria are being satisfied. Mesh generation must be related to the solution through computable estimates of discretization errors. Thus, an iterative process of alternate mesh and solution generation evolves in an adaptive manner with the end result that the solution is computed to prescribed specifications in an optimal, or at least efficient, manner. While mesh generation and adaptive strategies are becoming available, major computational challenges remain. One, in particular, involves moving boundaries and interfaces, such as free-surface flows and fluid-structure interactions. A 3-week program was held from July 5 to July 23, 1993 with 173 participants and 66 keynote, invited, and contributed presentations. This volume represents written versions of 21 of these lectures. These proceedings are organized roughly in order of their presentation at the workshop. Thus, the initial papers are concerned with geometry and mesh generation and discuss the representation of physical objects and surfaces on a computer and techniques to use this data to generate, principally, unstructured meshes of tetrahedral or hexahedral elements. Themore » remainder of the papers cover adaptive strategies, error estimation, and applications. Several submissions deal with high-order p- and hp-refinement methods where mesh refinement/coarsening (h-refinement) is combined with local variation of method order (p-refinement). Combinations of mathematically verified and physically motivated approaches to error estimation are represented. Applications center on fluid mechanics. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.« less

GENERATION OF THE UNSTRUCTURED FE-GRIDS FOR COMPLEX 2D OBJECTS/NESTRUKTŪRINIŲ BE TINKLŲ GENERAVIMAS SUDĖTINGIEMS DVIMAČIAMS OBJEKTAMS

3D mesh adaptation. Optimization of tetrahedral meshes by advancing front technique

Mesh generation with adaptive finite element analysis

Mesh generation is a critical preprocessing step in Computational Fluid Dynamics. In ship hydrodynamics, existing mesh generation methods lack adaptability to complex hull surface geometries, necessitating repeated optimization. To address these issues, a new hybrid mesh generation strategy was proposed, integrating Non-Uniform Rational B-Spline surface interpolation, advancing front technique, hull surface curvature features, and mesh quality evaluation parameters. Firstly, the ship hull surface was partitioned into multiple regions, and each region was assigned a specific mesh type. Subsequently, the adaptively sized mesh was generated based on local curvature variations. Finally, the angle skewness was employed as an objective function to improve the mesh quality. In addition, considering the actual ship model as an example, the mesh generated by our method and conventional Laplacian smoothing method were used to perform first-order potential flow simulations, and the results were compared against the convergence values. The results indicated that our method has lower root mean square errors in computing the total non-viscous force, steady drift force and ship hull free floating Response Amplitude Operator. This method is applicable to numerical simulations of the ship potential flow, providing high-quality hull meshes for hydrodynamic analysis.

Numerical geometry and mesh generation is a cross-cutting technology that greatly influences its downstream meshbased computational technologies, such as computational fluid dynamics (CFD) and computational structural mechanics (CSM). However, this pre-processing step often is the most tedious and laborious one in the computational simulation cycle. Advances in core mesh generation algorithms have been steadily achieved throughout the past three decades. The popularity of unstructured meshes (tetrahedral, hexahedral, hybrid and polyhedral) facilitates the mesh generation step significantly. However, challenges remain in the CAD-to-mesh process. The papers in this volume were selected from the papers at the 15th International Meshing Roundtable, held 17–20 September 2006 in Birmingham, Alabama, USA. The conference was started by Sandia National Laboratories in 1992 as a small meeting of organizations striving to establish a common focus for research and development in the field of mesh generation. It is now an annual conference attended by researchers and developers from dozens of countries around the world. Selected by peer reviewers based on their perceived quality, originality, and contributions to the geometry and mesh generation technology development, these papers are collected into this special issue of the Journal of Engineers with Computers. As the editors of this special issue, we would like to express our sincere gratitude to the contributing authors, reviewers, and publishing staff for their efforts and contributions to make this possible.

Non-iterative generation of an optimal mesh for a blade passage using deep reinforcement learning

The 1st AIAA Geometry and Mesh Generation Workshop (GMGW-1) was held in conjunction with the AIAA Aviation Forum and Exposition 2017 and in collaboration with the 3rd AIAA Computational Fluid Dynamics (CFD) High Lift Prediction Workshop (HiLiftPW-3). As the first AIAA workshop on these topics, GMGW-1's broad objectives were to assess the current state-of-the art in geometry preprocessing and mesh generation technology as well as software as applied to aircraft and spacecraft systems. The workshop was intended to identify and develop understanding of areas of needed improvement in terms of performance, accuracy, and applicability. It was also to provide a foundation for documenting best practices for geometry preprocessing and mesh generation. The genesis of GMGW-1 is found in the indictments levied against geometry preprocessing and mesh generation - not undeservedly - by the NASA CFD Vision 2030 Study. In order to create a reference against which future progress in geometry preprocessing and mesh generation can be measured, the organizers of GMGW-1, with the assistance of the organizers of HiLiftPW- 3, focused GMGW-1 on generation of meshes of the NASA High Lift Common Research Model (HL-CRM). Some of the generated meshes were provided for use by the participants in HiLiftPW-3. All meshes and the processes by which they were generated were analyzed by GMGW-1 as a first assessment of state of the art practices. The results of GMGW-1 added quantitative detail to known problem areas including geometry modeling, data interoperability, and amount of human intervention. They do provide a clear path toward a vision of geometry preprocessing and mesh generation in the year 2030. The next milepost along this path will be a second workshop.

Volutes are widely used in industrial process, refrigeration system, small gas turbines and gas pipeline centrifugal compressors as the transition from the impeller-diffuser to the pipings, because of their simple structure, ease of production and wide operating range. This paper illustrates a new design tool that incorporates a new volute design system that integrates and automates geometry generation, grid generation and aerodynamic analysis. In optimizing the available technology in terms of grid generation, CFD, and computer graphics, the program will utilize existing technology used by industry to generate a powerful volute design tool. The design tool is programmed in a way that integrates the features and methods a designer would use for volute design. This is fundamentally by means of geometrical constraints and/or functional relationships. Grids can be generated in minutes accommodating geometrical changes thus reducing the bottlenecks associated with geometry/grid generation for CFD applications. Prior to most CFD analysis work, a structured grid must be produced ensuring high quality such that convergence is assured and the time to convergence of the solution is minimized. However, there are usually only a few people that have the required skills to produce the geometry and generate a high quality structured grid. In essence, the tool provides a sidestep around both the geometry generation and the grid generation process. It automates the process such that anybody can produce a high quality grid from the geometry and move straight to the CFD component of the work and hence can incorporate CFD as part of the design process. The volute design tool will enable the user to generate a family of volutes and display 2D volute cross sections and 3D solid models of the scroll, diffuser inlet, discharge conic, and connecting channel. Separate interfaces will be written to accommodate the different operating systems. The geometry generation will be written in windows however, a separate interface will be written to produce the grid being compatible in NT, Unix, and Linux platforms.

Geometric modeling and mesh generation play important roles in mesh-based computational simulations in applications in science, engineering, and medicine. Geometric modeling and mesh generation are often the most laborious steps in the computational pipeline. Although significant progress has been made in these areas over the past three and a half decades, they remain important research areas today. More recently, mesh generation algorithms have been developed for new applications, for example, in medicine and energy. In addition, mesh optimization, the connection of meshes to linear solvers for the solutions of numerical partial differential equations, and mesh adaption are some of the other important considerations once an initial mesh has been generated. As computational simulations become more involved, parallel mesh algorithms are developed in order to solve larger and more complex problems. Important contributions have been made in algorithms, theory, and software in these research areas. The papers in this volume were selected from the papers at the 19th International Meshing Roundtable, held October 3–6, 2010 in Chattanooga, TN, USA. The conference was started by Sandia National Laboratories in 1992 as a small meeting of organizations striving to establish a common focus for research and development in the field of mesh generation. It is now an annual conference attended by researchers and developers from dozens of countries around the world. Based on input from peer reviewers based on their perceived quality, originality, technical soundness, and significance, the authors of these 11 papers received the top review scores and were invited to submit an extended version of their article for publication in this special issue of Engineering with Computers. As editors of this special journal issue, we would like to thank the authors who contributed to this volume, the reviewers of the papers, as well as the Engineering with Computers publishing staff. It is their efforts which make this special journal issue possible. Guest Editors: Suzanne M. Shontz and Yongjie Zhang.

Geometry and mesh generation for high fidelity computational simulations using non-uniform rational B-splines

A computational framework for derivative-free optimization of cardiovascular geometries

This paper discusses current work on STRUCTURAL ASPECTS OF the design optimization of a Truss Braced Wing (TBW) configuration. These wings offer significat potential for performance improvements in terms of fuel efficiency, but also offer challenges for a structural designer. The details of the structural analysis and design methodology are presented. Two different design methodologies are discussed: structural sizing based on beam idealization considering only bending stiffness and static analysis, and a finite element based sizing optimization approach including aeroelastic effects. The paper reports all aspects of the two approaches: design parameterization, model geometry and mesh generation, analysis and optimization. The first approach has been used in the past at Virginia Tech for Multidisciplinary Design Optimization (MDO) studies of a Strut-Braced Wing (SBW), and extensions to sizing of a more general TBW configuration are discussed. The second approach is used to perform some parametric studies presented here. Comparative studies are performed for wings designed for rigid and flexible trim subject to static stress constraints. The aeroelastic performance of some TBW configurations is investigated. Only structural sizing parameters are treated as design variables. Conclusions are drawn from these results for guidance to the ongoing MDO studies of the TBW, to be reported in future papers.

A computational procedure for part design