Visualization Lagrangian Visualization of Natural Convective Flows Luis M. de la Cruz, Eduardo Ramos, and Victor Godoy This paper presents a visualization technique which shows the geometric deformation of a fluid moving by natural convection inside a cubic container. The technique is based on intensive numerical calculations and the use of sophisticated visualization tools. The convective motion is produced by maintaining the temperatures of two opposite vertical walls of the container at constant value but different values. All other sides are considered to be thermally insulated. The wall temperatures oscillate as a function of time. Due to the combined effect of time-dependent temperature difference and gravity acceleration, vortices are generated in different zones of the container. Under appropriate circumstances, the vortices may lead to mixing. The flow details are obtained by numerical integration of time dependent governing equations for mass, momentum and energy. The flow visualization is obtained using Lagrangian particle tracking of a set of points distributed on a closed surface. The deformation of the surface contains information about dynamics of the flow; in particular, it is possible to identify zones where flow stretching and foldings occur. An estimation of the error by reversal is given. Calculations and visualizations were made in an Origin 2000 and in an Onix computer respectively. Strategies for Visual Supercomputing Scott Ellman This talk will summarize the current state of visualization for supercomputing environments, including the emergence of the Visual Supercomuting paradigm. It will then look at how Visual Supercomputing can be used to increase the insight obtained from supercomputing calculations, and will conclude with a discussion of how various Visual Supercomputing sites are implementing these strategies. New Techniques in High Performance Visualization Jim Foran Visualization is a critical aspect in understanding results from supercomputing calculations. However, in many supercomputing environments, the visualization techniques used are limited by the capabilities of desktop workstations and do not match the requirements of the end user. This presentation describes several new visualization paradigms that eliminate obstacles to understanding, increase the involvement of scientists and engineers in the analysis of their data, and increase the value of supercomputing and visualization assets to the organization. The Use of Virtual Reality Techniques in Industrial Applications Lori Freitag, Darin Diachin, Daniel Heath, and Tim Urness At Argonne National Laboratory we have successfully used the CAVE virtual reality environment for interactive engineering and analysis in two industrial combustion applications: the design of injective pollution control systems for commercial boilers and the analysis of different fuel types for a new burner in aluminum smelting furnaces. In this talk we will describe the applications in some detail, the visualization techniques developed, the software mechanisms used to create data structure independent toolkits, and the use of interactive virtual reality environments to add value to engineering analysis and design. Distributed Memory Octree Algorithms for Interactive, Adaptive, Multiresolution Visualization of Large Data Sets Raymond Loy and Lori Freitag The interactive visualization and exploration of large scientific data sets is a challenging and difficult task; their size often far exceeds the performance and memory capacity of even the most powerful graphics workstations. To address this problem, we have created a technique that combines hierarchical data reduction methods with parallel computing to allow interactive exploration of large data sets while retaining full-resolution capability. The hierarchical representation is built in parallel by strategically inserting field data into an octree data structure. We provide functionality that allows the user to interactively adapt the resolution of the reduced data sets so that resolution is increased in regions of interest without sacrificing local graphics performance. We describe the creation of the reduced data sets using a parallel octree, the software architecture of the system, and the performance of this system on the data from a Rayleigh-Taylor instability simulation. Reality Monster Volume Rendering James Painter, Al McPherson, and Pat McCormick Texture based volume rendering algorithms can be used to exploit high performance graphics accelerators such as the SGI IR (Infinite Reality) for interactive volume rendering. A single IR can interactively render a 64M voxel data set (256^3). Working with SGI, we have chained together multiple IR pipes in order to enable rendering of even larger problems. With 16 IR pipes we have been able to render billion cell data sets (1024^3) at approximately 5 frames per second. We have architected an I/O system that enables us to interactively page through billion cell time histories at approximately the same rate. This I/O system is able to page texture data from disk at 5 Gigavoxels per second. Interacting with Gigabyte Volume Datasets on the Origin2000 Steve Parker, Peter Shirley, Yarden Livnat, Charles Hansen, Peter-Pike Sloan, and Michael Parker We present a parallel ray tracing program that computes isosurfaces of large-scale volume datasets interactively. The system is shown for the gigabyte Visable Woman dataset. Animation of Hairpin Vortices in a Laminar-Boundary-Layer Flow Past a Hemisphere Henry Tufo, Paul Fischer, Mike Papka, and Matt Szymanski In an effort to understand the vortex dynamics of coherent structures in turbulent and transitional boundary layers, we consider direct numerical simulation of the interaction between a flat-plate-boundary-layer flow and an isolated hemispherical roughness element. Of principal interest is the evolution of hairpin vortices that form an interlacing pattern in the wake of the hemisphere, lift away from the wall, and are stretched by the shearing action of the boundary layer. Using animations of unsteady, three-dimensional representations of this flow produced by a vtk enhanced CAVE library developed at Argonne National Laboratory, we identify and study several key features in the evolution of this complex vortex topology not previously observed in other visualization formats. Table of Contents | Author Index | CUG Home Page | Home (Title Page)