基于PDAE系统的ANSYS二次开发

为了满足发电设备制造企业对通用CAE分析软件（如ANSYS）的集成整合需求,提高设计分析效率,首先分析了ANSYS的参数化设计语言APDL和JAVA对APDL的封装技术,提出了一种通过APDL方式对ANSYS进行二次开发的方法,并已应用在＂发电设备产品创新开发工程分析环境系统＂（PDAE）上。该方法允许用户在定制生成APDL模板文件后,在PDAE系统中修改相关参数,由系统自动生成输入文件并远程调用服务器端的ANSYS进行分析计算,生成的结果文件最终将返回至PDAE中显示。此方法可简化繁琐的设计分析过程,有效提高工程分析人员的设计效率。     

Index analysis and reduction of systems of quasi-linear partial-differential and algebraic equations

To reliably solve PDAE models in established equation-oriented modeling environments (i) certain mathematical properties are to be fulfilled and (ii) the specified initial- and boundary conditions are to be consistent. For an assessment of both of these aspects an important theoretical framework is the concept of index. In this contribution we propose a new method for a systematic index reduction of quasi-linear PDAE systems. The general idea is to reveal quasi-linear combinations of the differential quantities in the high-index model which are invariant with respect to a specific independent variable. By using these quasi-linear combinations as templates for symbolic manipulations, additional algebraic constraints become explicit. These explicit constraints are then used for index reduction yielding low-index PDAE models. The procedure is demonstrated in the context of a typical modeling work-flow for modeling problems of a tubular reactor, diffusive charge transport in electrolyte mixtures and incompressible fluid flow.     

Comparative Study of Different Techniques for Numerical Reservoir Simulation

Abstract

Many physical processes such as multiphase flow in heterogeneous porous media are described by partial differential algebraic equations (PDAEs) as a set of partial differential, ordinary differential and algebraic equations. However, due to lack of exact analytical solution for most PDAEs, numerical methods should be used to approximate their solution. The main contribution of this article is a comparison among the features of such numerical methods for oil and gas reservoir simulation. Different gridding techniques have been included in this comparison to find the most suitable numerical scheme to simulate multiphase flow in heterogeneous porous media.