Overset grid applications on distributed memory MIMD computers

Analysis of modern aerospace vehicles requires the computation of flowfields about complex three dimensional geometries composed of regions with varying spatial resolution requirements. Overset grid methods allow the use of proven structured grid flow solvers to address the twin issues of geometrical complexity and the resolution variation by decomposing the complex physical domain into a collection of overlapping subdomains. This flexibility is accompanied by the need for irregular intergrid boundary communication among the overlapping component grids. This study investigates a strategy for implementing such a static overset grid implicit flow solver on distributed memory, MIMD computers; i.e., the 128 node Intel iPSC/860 and the 208 node Intel Paragon. Performance data for two composite grid configurations characteristic of those encountered in present day aerodynamic analysis are also presented

Numerical Solution of Buoyancy Induced Motion of a Hydrogen Flame Bubble (Combustion, Convection)

288 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986.Mixtures of hydrogen and air, when confined to a standard flammability tube, exhibit a remarkable flame structure in the neighborhood of the lean limit. The subject of this dissertation is the investigation of this fine structure, referred to as "flame bubbles", brought about by cellular type instability. We consider the numerical simulation of steady, buoyancy induced motion of an isolated hydrogen flame bubble, with the intention of gaining an understanding of the qualitative features of the associated flow field.The mathematical model is derived from thin flame sheet approximation based on high activation energy asymptotics. This leads to the numerical solution of the variable density Navier-Stokes equations and the energy equation in an axisymmetric geometry. Use of the finite difference discretization gives rise to a system of non-linear equations, which is solved using the Newton-Raphson method. The large sparse system of non-symmetric linear equations corresponding to the Jacobian matrix is then solved using direct as well as iterative schemes.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

A comparison of PDE-based non-linear anisotropic diffusion techniques for image denoising

PDE-based, non-linear di#usion techniques are an e#ective way to denoise images. In a previous study, we investigated the e#ects of di#erent parameters in the implementation of isotropic, non-linear di#usion. Using synthetic and real images, we showed that for images corrupted with additive Gaussian noise, such methods are quite e#ective, leading to lower mean-squared-error values in comparison with spatial filters and wavelet-based approaches. In this paper, we extend this work to include anisotropic di#usion, where the di#usivity is a tensor valued function which can be adapted to local edge orientation. This allows smoothing along the edges, but not perpendicular to it. We consider several anisotropic di#usivity functions as well as approaches for discretizing the di#usion operator that minimize the mesh orientation e#ects. We investigate how these tensor-valued di#usivity functions compare in image quality, ease of use, and computational costs relative to simple spatial filters, the more complex bilateral filters, wavelet-based methods, and isotropic non-linear di#usion based techniques

In vitro pro-inflammatory enzyme inhibition and anti-oxidant potential of selected Sri Lankan medicinal plants

Abstract Background The extracts of the ten selected Sri Lankan medicinal plants have been traditionally used in the treatment of inflammatory mediated diseases. The extracts were investigated for anti-inflammatory and anti-oxidant potential in vitro to identify bio-active extracts for further chemical characterization. Methods In vitro anti-inflammatory activities of total ethanol extracts were investigated measuring the inhibitory activities of four pro-inflammatory enzymes, arachidonate-5- lipoxygenase (A5-LOX), hyaluronidase (HYL), xanthine oxidase (XO) and inducible nitric oxide (iNO) synthase. Cytotoxicity of extracts were determined by MTT assay. Oxidative burst inhibition (OBI) on human whole blood (WB) and isolated polymorphoneutrophils (PMNs) was carried out for a selected bio-active extract. Anti- oxidant activities of the extracts were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, ferric reducing antioxidant power (FRAP), ferrous ion chelation (FIC) and oxygen radical absorbance capacity (ORAC) assays. Total polyphenol and total Flavonoid contents of the extracts were also determined. The most active plant extract was analysed using Gas chromatography-Mass spectrometry (GC-MS) and High Performance Liquid Chromatography (HPLC). Results The ethanol bark extract of Flacourtia indica showed the highest A5-LOX (IC50: 22.75 ± 1.94 g/mL), XO (70.46 ± 0.18%; 250 μg/mL) and iNOs inhibitory activities on LPS- activated raw 264.7 macrophage cells (38.07 ± 0.93%; 500 μg/mL) with promising OBI both on WB (IC50: 47.64 2.32 μg/mL) and PMNs (IC50: 5.02 0.38 μg/mL). The highest HYL inhibitory activity was showed by the leaf extracts of Barathranthus nodiflorus (42.31 ± 2.00%; 500 μg/mL) and Diospyros ebenum (41.60 ± 1.18%; 500 μg/mL). The bark and leaf extracts of Callophyllum innophyllum (IC50: 6.99 ± 0.02 μg/mL) and Symplocus cochinchinesis (IC50: 9.85 ± 0.28 μg/mL) showed promising DPPH free radical scavenging activities. The GC-MS analysis of ethanol bark extract of F. indica showed the presence of two major bio-active compounds linoleic acid ethyl ester and hexadecanoic acid, ethyl ester (> 2% peak area). The HPLC analysis showed the presence polyphenolic compounds. Conclusion The ethanol bark extract of F. indica can be identified as a potential candidate for the development of anti-inflammatory agents, which deserves further investigations. The bio-active plant extracts may be effectively used in the applications of cosmetic and health care industry