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作者： Maunus, Jeremy Grace, Sheryl M. Sondak, Douglas L. Boston University Boston MA 02215 United States Department of Mechanical Engineering Denmark Scientific Computing and Visualization United States

ISBN: (纸本)9781600867446

The prediction of noise produced by fan-wake interaction with the fan exit guide vane (FEGV) is studied. The acoustic response of the FEGV is computed using LINFLUX, a three-dimensional, frequency-domain, linearized Euler solver for turbomachinery. The research focuses on tonal noise predictions for the advanced ducted propulsor (ADP) and the source diagnostic test (SDT) scaled turbofan rigs. The sensitivity of the 2BPF noise prediction to the inflow specification is quantified. Inflow models are generated based on both experimental and computational fan-wake data. The computational data are provided by four different Reynolds-Averaged Navier Stokes (RANS) computational fluid dynamic (CFD) solutions. When compared to experimental results, the computations provide comparable mean flow solutions but overpredict the wake deficit. The CFD solutions differ more for higher wheel speed cases, especially in the tip region. It is shown that inputs generated from the various experimental and CFD data also differ, but that these differences weakly impact the prediction of the sound power level (PWL) at the lower wheel speed. At the higher wheel speeds, where the differences in the inputs near the tip are greatest, the PWL reflects this difference. For a given wheel speed, the predictions using input values based on the different CFD data and the experimental wake data agree to within 5 dB. However, they vary from the experimentally measured acoustic PWLs by up to 14 dB. © 2010 by J. Maunus and S. Grace.

关键词： Computational fluid dynamics

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Large data visualization on distributed memory multi-GPU clusters 2

Large data visualization on distributed memory multi-GPU clu...

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2nd ACM SIGGRAPH / Eurographics on High-Performance Graphics, HPG 2010

作者： Fogal, Thomas Childs, Hank Shankar, Siddharth Krüger, Jens Bergeron, R. Daniel Hatcher, Philip Scientific Computing and Imaging Institute University of Utah United States Department of Computer Science University of New Hampshire United States Lawrence Berkeley National Laboratory United States Interactive Visualization and Data Analysis Group DFKI Germany

ISBN: (纸本)9783905674262

Data sets of immense size are regularly generated on large scale computing resources. Even among more traditional methods for acquisition of volume data, such as MRI and CT scanners, data which is too large to be effectively visualized on standard workstations is now commonplace. One solution to this problem is to employ a 'visualization cluster,' a small to medium scale cluster dedicated to performing visualization and analysis of massive data sets generated on larger scale supercomputers. These clusters are designed to fit a different need than traditional supercomputers, and therefore their design mandates different hardware choices, such as increased memory, and more recently, graphics processing units (GPUs). While there has been much previous work on distributed memory visualization as well as GPU visualization, there is a relative dearth of algorithms which effectively use GPUs at a large scale in a distributed memory environment. In this work, we study a common visualization technique in a GPU-accelerated, distributed memory setting, and present performance characteristics when scaling to extremely large data sets. The Eurographics Association 2010.

关键词： Graphics processing unit

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Large Data visualization on Distributed Memory Multi-GPU Clusters 10

Large Data Visualization on Distributed Memory Multi-GPU Clu...

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Conference on High-performance Graphics

作者： Thomas Fogal Hank Childs Siddharth Shankar Jens Kriiger R. Daniel Bergeron Philip Hatcher Scientific Computing & Imaging Institute University of UtahDepartment of Computer Science University of New Hampshire Lawrence Berkeley National Laboratory Scientific Computing & Imaging Institute University of Utah Interactive Visualization and Data Analysis Group DFKI Germany Department of Computer Science University of New Hampshire

ISBN: (纸本)9781617827242

关键词： distributed memory Data visualisation visualization Dataset supercomputer Representation of data performance characteristics

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Maximizing adaptivity in hierarchical topological models using cancellation trees

Maximizing adaptivity in hierarchical topological models usi...

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Workshop on Mathematical Foundations of scientific visualization, Computer Graphics, and Massive Data Exploration, 2004

作者： Bremer, Peer-Timo Pascucci, Valerio Hamann, Bernd Department of Computer Science University of Illinois Urbana-Champaign United States Center for Applied Scientific Computing Lawrence Livermore National Laboratory United States Institute for Data Analysis and Visualization Department of Computer Science University of California Davis United States

ISBN: (纸本)9783642543005

We present a highly adaptive hierarchical representation of the topology of functions defined over two-manifold domains. Guided by the theory of Morse–Smale complexes, we encode dependencies between cancellations of critical points using two independent structures: a traditional mesh hierarchy to store connectivity information and a new structure called cancellation trees to encode the configuration of critical points. Cancellation trees provide a powerful method to increase adaptivity while using a simple, easy-to-implement data structure. The resulting hierarchy is significantly more flexible than the one previously reported (IEEE Trans. Vis. Comput. Graph. 10(4):385–396, 2004). In particular, the resulting hierarchy is guaranteed to be of logarithmic height. © 2009 Springer-Verlag Berlin Heidelberg.

关键词： Trees (mathematics)

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Compression and occlusion culling for fast isosurface extraction from massive datasets

Compression and occlusion culling for fast isosurface extrac...

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Workshop on Mathematical Foundations of scientific visualization, Computer Graphics, and Massive Data Exploration, 2004

作者： Gregorski, Benjamin Senecal, Joshua Duchaineau, Mark Joy, Kenneth I. Center for Applied Scientific Computing Lawrence Livermore National Laboratory 7000 East Avenue LivermoreCA94551 United States Institute for Data Analysis and Visualization Department of Computer Science University of California Davis One Shields Avenue DavisCA95616 United States

ISBN: (纸本)9783642543005

We present two algorithms for data compression and occlusion culling that improve interactive, adaptive isosurface extraction from large volume datasets. Our algorithm, based on hierarchical tetrahedral meshes defined by longest edge bisection, allows arbitrary isosurfaces to be adaptively extracted at interactive rates from losslessly compressed volumes where the region of interest, determined at runtime by user interaction, is decompressed on-the-fly. For interactive applications, we exploit frame-to-frame coherence between consecutive views to simplify the mesh structure in occluded regions and eliminate occluded triangles significantly reducing the complexity of the visualized surface and the underlying multiresolution volume representation. We extend the use of hardware accelerated occlusion queries to adaptive isosurface extraction applications where the surface geometry and topology change with the level-of-detail and view-point and the user can select an arbitrary isovalue for visualization. © 2009 Springer-Verlag Berlin Heidelberg.

关键词： Extraction

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Feature-based comparison of flow fields around a three-element high-lift configuration with active flow control

Feature-based comparison of flow fields around a three-eleme...

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作者： Günther, B. Thiele, F. Weinkauf, T. Sahner, J. Hege, H.-C. Institute of Fluid Mechanics and Engineering Acoustics Berlin University of Technology Müller-Breslau-Straße 8 D-10623 Berlin Germany Department Visualization Division Scientific Computing Zuse Institute Berlin Takustraße 7 D-14195 Berlin Germany

ISBN: (纸本)9781563479427

The control of the flow over the flap of a three-element high-lift configuration is investigated numerically by solving the unsteady Reynolds-averaged Navier-Stokes equations (URANS). At a Reynolds number of Re = 1 · 106 the flow is perturbed by periodic blowing/suction through a slot near the flap leading edge. The main focus is on the mechanisms of separation control, for which flow field structures at two different excitation parameters are studied. The simulations are conducted using a swept wing of infinite span in order to study the impact of different excitation parameters. The method of feature-based extraction will be used to identify dominant large scale structures in the unforced and excited flow field. Copyright © 2008 by B. Günther, F. Thiele, T. Weinkauf, J. Sahner and H.-C. Hege.

关键词： Vortex flow

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Preface

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Mathematics and visualization 2009年第3期18卷 V-VI页

作者： Hege, Hans-Christian Polthier, Konrad Scheuermann, Gerik Konrad-Zuse-Zentrum für Informationstechnik Berlin Devision Scientific Computing Department Visualization and Data Analysis Takustraße 7 Berlin14195 Germany Freie Universität Berlin Institut für Mathematik Arnimallee 6 Berlin14195 Germany Universität Leipzig Fakultät für Mathematik und Informatik Institut für Informatik Postfach 100920 Leipzig04009 Germany

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Feature Identification and Extraction in Function Fields

Feature Identification and Extraction in Function Fields

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9th Joint Eurographics/IEEE VGTC Symposium on visualization, EuroVis 2007

作者： Anderson, John C. Gosink, Luke J. Duchaineau, Mark A. Joy, Kenneth I. Institute for Data Analysis and Visualization Department of Computer Science University of California Davis United States Center for Applied Scientific Computing Lawrence Livermore National Laboratory

ISBN: (纸本)9783905673456

We present interactive techniques for identifying and extracting features in function fields. Function fields map points in n-dimensional Euclidean space to 1-dimensional scalar functions. Visual feature identification is accomplished by interactively rendering scalar distance fields, constructed by applying a function-space distance metric over the function field. Combining visual exploration with feature extraction queries, formulated as a set of function-space constraints, facilitates quantitative analysis and annotation. Numerous application domains give rise to function fields. We present results for two-dimensional hyperspectral images, and a simulated time-varying, three-dimensional air quality dataset. © The Eurographics Association 2007.

关键词： Air quality

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CFD computation of fan interaction noise

CFD computation of fan interaction noise

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ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007

作者： Grace, Sheryl M. Sondak, Douglas L. Dorney, Daniel J. Logue, Michaela Department of Aerospace and Mechanical Engineering Boston University 110 Cummington St. BostonMA02215 United States Scientific Computing and Visualization Boston University BostonMA02215 United States Fluid Dynamics Branch NASA Marshall Space Flight Center AL35812 United States Aerospace and Mechanical Engineering Department University of Notre Dame Notre DameIN45665 United States

ISBN: (纸本)0791843025

In this study, a 3-D, unsteady, Reynolds-averaged Navier- Stokes (RANS) CFD code coupled to an acoustic calculation is used to predict the contribution of the exit guide vanes to tonal fan noise downstream. The configuration investigated is that corresponding to the NASA Source Diagnostic Test (SDT) 22-in fan rig. One configuration from the SDT matrix is considered here: The approach condition, and outlet guide vane count designed for cut-off of the blade passage frequency. In this chosen configuration, there are 22 rotor blades and 54 stator blades. The stators are located 2.5 tip chords downstream of the rotor trailing edge. The RANS computations are used to obtain the spectra of the unsteady surface pressure on the exit guide vanes. The surface pressure at the blade passage frequency and its second harmonic are then integrated together with the Green's function for an annular duct to obtain the pressure at locations in the duct. Comparison of the computed sound power level at the exhaust plane with experiment show good agreement at the cut-on circumferential mode. The results from this investigation validate the use of the CFD code along with the acoustic model for downstream fan noise predictions. This validation enables future investigations such as the effect of duct variation on the exhaust tonal power level and the validity of using this method for predicting broadband noise levels. Copyright © 2007 by ASME.

关键词： Stators

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A geometric multigrid approach to solving the 2D inhomogeneous Laplace equation with internal Dirichlet boundary conditions

A geometric multigrid approach to solving the 2D inhomogeneo...

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IEEE International Conference on Image Processing

作者： L. Grady T. Tasdizen R. Whitaker Department of Imaging and Visualization Siemens AG Corporate Research and Development Princeton NJ USA Scientific Computing and Imaging Institute Salt Lake UT USA

The inhomogeneous Laplace (Poisson) equation with internal Dirichlet boundary conditions has recently appeared in several applications to image processing and analysis. Although these approaches have demonstrated quality results, the computational burden of solution demands an efficient solver. Design of an efficient multigrid solver is difficult for these problems due to unpredictable inhomogeneity in the equation coefficients and internal Dirichlet conditions with arbitrary location and value. We present a geometric multigrid approach to solving these systems designed around weighted prolongation/restriction operators and an appropriate system coarsening. This approach is compared against a modified incomplete Cholesky conjugate gradient solver for a range of image sizes. We note that this approach applies equally well to the anisotropic diffusion problem and offers an alternative method to the classic multigrid approach of Acton (1998).

关键词： Laplace equations Boundary conditions Poisson equations Image segmentation Pixel Image processing Anisotropic magnetoresistance visualization Educational institutions Buildings

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