Gordon Bancroft

FAST: a multi-processed environment for visualization of computational fluid dynamics

The authors discuss FAST (flow analysis software toolkit), an implementation of a software system for fluid mechanics analysis. Visualization of computational aerodynamics requires flexible, extensible, and adaptable software tools for performing analysis tasks. An overview of FAST is given, and its architecture is discussed. Interactive visualization control is addressed. The advantages and disadvantages of FAST are discussed.<<ETX>>

Flow visualization of CFD using graphics workstations

High performance graphics workstations are used to visualize the fluid flow dynamics obtained from supercomputer solutions of computational fluid dynamic programs. The visualizations can be done independently on the workstation or while the workstation is connected to the supercomputer in a distributed computing mode. In the distributed mode, the supercomputer interactively performs the computationally intensive graphics rendering tasks while the workstation performs the viewing tasks. A major advantage of the workstations is that the viewers can interactively change their viewing position while watching the dynamics of the flow fields. An overview of the computer hardware and software required to create these displays is presented. For complex scenes the workstation cannot create the displays fast enough for good motion analysis. For these cases, the animation sequences are recorded on video tape or 16 mm film a frame at a time and played back at the desired speed. The additional software and hardware required to create these video tapes or 16 mm movies are also described. Photographs illustrating current visualization techniques are discussed. Examples of the use of the workstations for flow visualization through animation are available on video tape.

Scientific visualization in computational aerodynamics at NASA Ames Research Center

Tools specifically oriented toward flow analysis problems are described. The approach is oriented toward performing graphics calculations on the supercomputer and using high-end workstations as rendering engines to display flow fields generated by aircraft flight. A suite of software provides both display and interactive analysis capability. Also described is animation hardware featuring Winchester disk technology, which allows the storage of more than one gigabyte of data and supports editing, special effects, and video output.<<ETX>>

Visualization of supercomputer simulations in physics

Recent advances in computer graphics hardware and software have resulted in major improvements in our ability to experience computer simulations of physics by viewing dynamic three-dimensional scenes representing the simulations. This paper describes the hardware and software tools and techniques in use at NASAs Numerical Aerodynamic Simulation Facility for visualization of computational fluid dynamics. The visualization process is illustrated by video tapes and stereo pictures (available from the authors). The hardware consists of high-performance graphics workstations connected to the supercomputer with high-bandwidth lines, a frame buffer connected to the supercomputer with UltraNet, a digital video recording system, and film recorders. The software permits the scientist to dynamically view the 3D scenes, to zoom into a region of interest, and to rotate his viewing position to study any region of interest in more detail. The software also provides automated animation and video recording of the scenes. The digital effects unit on the video system facilitates comparison of computer simulations with flight or wind tunnel experiments. The current environment for computer simulations of physics is compared with an “ideal” environment to illustrate that major improvements in tools to help the scientist experience the simulations can be made by providing for a more natural and responsive user-interface, increasing the display field of view, and increasing the rate of scene creation.

Tools for 3D scientific visualization in computational aerodynamics at NASA Ames Research Center

The purpose of this paper is to describe the tools and techniques in use at the NASA Ames Research Center for performing visualization of computational aerodynamics, for example visualization of flow fields from computer simulations of fluid dynamics about vehicles such as the Space Shuttle. The hardware used for visualization is a high-performance graphics workstation connected to a super computer with a high speed channel. At present, the workstation is a Silicon Graphics IRIS 3130, the supercomputer is a CRAY2, and the high speed channel is a hyperchannel. The three techniques used for visualization are post-processing, tracking, and steering. Post-processing analysis is done after the simulation. Tracking analysis is done during a simulation but is not interactive, whereas steering analysis involves modifying the simulation interactively during the simulation. Using post processing methods, a flow simulation is executed on a supercomputer and, after the simulation is complete, the results of the simulation are processed for viewing. This is by far the most commonly used method for visualization of computational aerodynamics. The next two methods are much more desirable, yet much less common given the current state of supercomputer and workstation evolution and performance. Both of these are more sophisticated methods because they involve analysis of the flow codes as they evolve. Tracking refers to a flow code producing displays that give a scientist some indication how his experiment is progressing so he could, perhaps, change some parameters and then restart it. Steering refers to actually interacting with the flow codes during execution by changing flow code parameters. (Steering methods have been employed for grid generation pre-processing as well to substantially reduce the time it takes to construct a grid for input to a flow solver). When the results of the simulation are processed for viewing by distributing the process between the workstation and the supercomputer, it is called distributed processing. This paper describes the software in use and under development at NASA Ames Research Center for performing these types of tasks in computational aerodynamics. Workstation performance issues, benchmarking, and high-performance networks for this purpose are also discussed as well as descriptions of other hardware for digital video and film recording. A new software environment, FAST, is introduced that is currently being developed at NASA Ames for implementation on workstations that will be procured in the latter half of 1989. This modular software environment will take advantage of the multiple processor and large memory configurations and other features as specified in the NASA RFP for these workstations and is a natural evolution of the techniques described in this paper.

3-D graphics applications in fluid flow simulations

The Fluid Dynamics Division of the NASA Ames Research Center is using high performance interactive computer graphics to help visualize flow fields from computer simulations of fluid dynamics about vehicles such as the space shuttle. In current configurations, computational solutions of the flow field are obtained from Cray supercomputers. These solutions are then transferred to workstations for creation and interactive viewing of dynamics 3-D displays of the flow fields. Specific animated sequences can be created for viewing on the workstation or for recording on video tape of 16 mm movies with the aid of specialized software that permits easy editing and automatic tweening of the sequences. The software and hardware required to generate and record these displays are detailed.<<ETX>>