A multiblock/multilevel mesh refinement procedure for CFD computations

A multiblock/multilevel algorithm with local refinement for general two‐ and three‐dimensional fluid flow is presented. The patched‐based local refinement procedure is presented in detail and algorithmic implementations are also presented. The multiblock implementation is essentially block‐unstructured, i.e. each block having its own local curvilinear co‐ordinate system. Refined grid patches can be put anywhere in the computational domain and can extend across block boundaries. To simplify the implementation, while still maintaining sufficient generality, the refinement is restricted to a refinement of the grid successively halving the grid size within a selected patch. The multiblock approach is implemented within the framework of the well‐known SIMPLE solution strategy. Computational experiments showing the effect of using the multilevel solution procedure are presented for a sample elliptic problem and a few benchmark problems of computational fluid dynamics (CFD). Copyright © 2001 John Wiley & Sons, Ltd.     

Software package for 3D viscous gas flow simulation on multiprocessor computer systems

A parallel software package designed for the numerical simulation of three-dimensional viscous gas flows is presented. The numerical algorithm is based on kinetically consistent difference schemes used on locally refined grids. The software package has been tested in various super-and subsonic flow problems. It provides an opportunity for the direct simulation of turbulent flows. The efficiency of parallelization is analyzed depending on the problem size and the number of processors.     

A numerical technique for laminar swirling flow at the interface between porous and homogenous fluid domains

There have been a few recent numerical implementations of the stress‐jump condition at the interface of conjugate flows, which couple the governing equations for flows in the porous and homogenous fluid domains. These previous demonstration cases were for two‐dimensional, planar flows with simple geometries, for example, flow over a porous layer or flow through a porous plug. The present study implements the interfacial stress‐jump condition for a non‐planar flow with three velocity components, which is more realistic in terms of practical flow applications. The steady, laminar, Newtonian flow in a stirred micro‐bioreactor with a porous scaffold inside was investigated. It is shown how to implement the interfacial jump condition on the radial, axial, and swirling velocity components. To avoid a full three‐dimensional simulation, the flow is assumed to be independent of the azimuthal direction, which makes it an axisymmetric flow with a swirling velocity. The present interface treatment is suitable for non‐flat surfaces, which is achieved by applying the finite volume method based on body‐fitted and multi‐block grids. The numerical simulations show that a vortex breakdown bubble, attached to the free surface, occurs above a certain Reynolds number. The presence of the porous scaffold delays the onset of vortex breakdown and confines it to a region above the scaffold. Copyright © 2008 John Wiley & Sons, Ltd.     

Thin viscous fluid film flows over rotating curvilinear surfaces

Thin viscous fluid film flows over rotating curvilinear surfaces are considered. The steady-state flow is studied for large and finite Ekman numbers. The possibility of obtaining a film of given thickness is considered. The wave formation on the surface of an inhomogeneous film and the development of nonlinear waves are also investigated. The film flow parameters in the cases of flow over a plane disk and a curvilinear surface are compared.     

GLOBAL SUPERCONVERGENCES OF THE DOMAIN DECOMPOSITION METHODS WITH NONMATCHING GRIDS

1. IlltroductionA nonconforming domain decomposition method with Lagrangian multipliers was proposedin [13]. The basic idea of this method is to deal with the nonconforming of nonmatching gridsby illtroducing the Lagrangian multipliers on interfaces of subdomains and its advalltages arethat it allows not only the incompatibility of the internal variables on the interface betweensubdomains, but also the discolltinuity of the boundary variables on the common venices ofsubdomains. Thus one can c…     

Metal grid technologies for flexible transparent conductors in large-area optoelectronics

Mechanically flexible optoelectronic devices such as flexible displays, touch-screens, wearable electronics and solar cells are attracting significant commercial interest. In these devices, a transparent conductor is an essential element that delivers or collects the electrical current to the active material while it allows light to enter or exit from the device. The transparent conductor is composed of a transparent conductive film and a metallic grid providing electrical conduction over the large area. In this article, we review the established processes used by the industry as well as emerging solution-based methods for processing metal grids. Furthermore, we review the issues and potentials of these emerging processes facing for large-area deployment. In the final section, we evaluate three applications of flexible transparent conductors in: perovskite-based solar cells, organic light emitting diodes and electrochromic windows.     

ELASTIC WAVES IN 3-D DISCRETE GRIDS

Wave motion in finite element models presents some characteristics different from thoseof wave motion in continuum,which leads to the errors and other special phenomena in finite elementsimulation of wave motion.The wave propagation in a 3-D finite element model is studied by utilizingthe formal solution in the paper,and the corresponding dispersion relations are derived.Then the mainproperties of wave motion in 3-D grids such as dispersion,cut-off frequency and polarization drift arediscussed.Characteristics different from those of wave motion in 2—D grids are revealed.     

三维离散网格中的弹性波动

本文采用形式解法研究三维有限元离散模型中波动的传播规律。文中由波动方程得到它的特征方程，进而给出了三维离散网格中波的频散关系，分析了三维网格中平面波、非匀匀波、寄生振荡及其它可能存在的运动形式的基本特点；详细讨论了平面波的频散、截止频率及偏振漂移等重要的不同于连续介质中的波动传播性质的特点，提示了其中不同于低维网格中 波动的现象。     

The multi-dimensional limiters for solving hyperbolic conservation laws on unstructured grids

Novel limiters based on the weighted average procedure are developed for finite volume methods solving multi-dimensional hyperbolic conservation laws on unstructured grids. The development of these limiters is inspired by the biased averaging procedure of Choi and Liu [10]. The remarkable features of the present limiters are the new biased functions and the weighted average procedure, which enable the present limiter to capture strong shock waves and achieve excellent convergence for steady state computations. The mechanism of the developed limiters for eliminating spurious oscillations in the vicinity of discontinuities is revealed by studying the asymptotic behavior of the limiters. Numerical experiments for a variety of test cases are presented to demonstrate the superior performance of the proposed limiters.