Applications and Innovations for Computational Electromagnetics

计算电磁学的应用和创新

• 批准号: RGPIN-2014-03984
• 负责人: Potter, Mike
• 金额: $ 2.7万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=587534
• 关键词: Applications; Innovations; Computational; Electromagnetics

Understanding the complex interactions of electromagnetic fields in devices and materials is critical in many application areas, ranging from high-speed circuit design to imaging and non-destructive testing. With the exponential growth in computing power experienced over the past several decades, there has been an ever-increasing demand for the tools that computational electromagnetics can provide to tackle engineering problems. Although there are dozens of methodologies for approaching such problems, the Finite-Difference Time-Domain (FDTD) method has become one of the de facto standards, because of its ability to robustly handle interactions of fields with complicated structures and materials. The applicability and efficiency of the method continues to be a vibrant research area, and in particular the method is being continually expanded to apply to a greater range of larger and more complicated modeling scenarios. The aims of the proposed research are to further improve and extend this method, and thus make it an even more indispensable tool for modeling of scenarios with complex material models and/or large structures. The work covered in this proposal consists of two main research areas. The first is the utilization of efficient wave sources in the FDTD method for modeling in complex environments. The second is to investigate the continued augmentation and innovation of the FDTD method on alternative grids for complex material modeling. The first area of research aims to overcome the restrictions placed upon modeling by complicated antenna geometries, by using the concept of equivalent sources to scale down the required computational resources (e.g. memory and processing power). In the FDTD method, equivalent sources can be used to accurately and efficiently represent radiating sources, thus obviating the need to model the source explicitly, allowing for considerable reduction in computer resource requirements, hence allowing for performance of quicker and/or larger simulations. This is particularly important where forward modeling is utilized in multiple iterations as part of an inverse scattering procedure. Such inversion procedures are used in applications where it is desired to build a map of the actual structure of the environment, for example for mapping underground structures to identify oil reservoirs (of particular importance for Canadian energy industries), or for building a tomographic map of the structure of the breast in order to identify malignant tumours. By improving the modeling capabilities of the underlying simulation tools we are inherently enhancing the capability to deal with more and more complicated and realistic practical problems of interest. The second area of research is intended to overcome the restrictions placed upon modeling by the original FDTD method, which is based upon a rectangular (Cartesian) layout of field components on a 3D grid. This choice of grid layout inherently introduces approximations and errors into the modeling, which can be partly mitigated by choosing a higher spatial resolution in simulation and/or better numerical appoximations, but at the cost of higher computational resources. Recently we have shown that both types of errors can be significantly reduced simply by structuring the FDTD method around a different grid from the outset, called the Lebedev grid. The grid also allows us to model complicated materials with higher accuracy compared to existing methods. In particular, augmentation of the method will allow us to model the propagation of waves in the earth-ionosphere system more accurately. This system is of partiuclar importance to Canadian reseachers involved with Space Physics and atmospheric/magnetospheric modelling.

了解器件和材料中电磁场的复杂相互作用在许多应用领域都是至关重要的，从高速电路设计到成像和无损检测。随着计算能力在过去几十年中经历的指数级增长，对计算电磁学可以提供的工具来解决工程问题的需求一直在不断增长。虽然有几十种方法可以解决这类问题，但时域有限差分(FDTD)方法由于其能够稳健地处理复杂结构和材料的相互作用而成为事实上的标准之一。该方法的适用性和效率仍然是一个充满活力的研究领域，特别是该方法正在不断扩展，以适用于更广泛的更大和更复杂的建模场景。研究的目的是进一步改进和扩展该方法，使其成为具有复杂材料模型和/或大型结构的场景建模中不可或缺的工具。本提案涵盖的工作包括两个主要研究领域。首先是利用FDTD方法中的有效波源进行复杂环境下的建模。二是研究了FDTD方法在复杂材料模拟的交替网格上的继续增强和创新。 第一个研究领域旨在通过使用等效源的概念来缩小所需的计算资源(例如，内存和处理能力)，从而克服复杂天线几何形状对建模的限制。在FDTD方法中，等效源可以被用来准确和有效地表示辐射源，从而消除了对源进行显式建模的需要，从而允许显著减少计算机资源需求，从而允许执行更快和/或更大的模拟。在作为反向散射过程的一部分在多次迭代中使用正演模拟的情况下，这尤其重要。这种反转过程用于需要构建环境的实际结构的地图的应用中，例如用于绘制地下结构以识别储油层(对加拿大能源工业特别重要)，或用于构建乳腺结构的断层扫描地图以识别恶性肿瘤。通过改进底层模拟工具的建模能力，我们内在地增强了处理越来越复杂和现实的感兴趣的实际问题的能力。 第二个研究领域旨在克服原始FDTD方法对基于矩形(笛卡尔)布局的建模施加的限制 三维栅格上的现场组件。这种网格布局的选择必然会在建模中引入近似和误差，这可以通过在模拟中选择更高的空间分辨率和/或更好的数值逼近来部分缓解，但代价是更高的计算资源。最近，我们已经证明，这两种类型的误差都可以通过从一开始就围绕一个不同的网格(称为Lebedev网格)构建FDTD方法来显著减少。与现有方法相比，网格还允许我们以更高的精度对复杂材料进行建模。特别是，该方法的增强将使我们能够更准确地模拟地球-电离层系统中的波的传播。这一系统对加拿大参与空间物理和大气/磁层建模的研究人员具有特别重要的意义。