Engineering topics

Vogel, Alison Andrews

Publications and source records attributed to Vogel, Alison Andrews.

4 records

NASA NTRS1991

Artificial Intelligence In Computational Fluid Dynamics

Paper compares four first-generation artificial-intelligence (Al) software systems for computational fluid dynamics. Includes: Expert Cooling Fan Design System (EXFAN), PAN AIR Knowledge System (PAKS), grid-adaptation program MITOSIS, and Expert Zonal Grid Generation (EZGrid). Focuses on knowledge-based ("expert") software systems. Analyzes intended tasks, kinds of knowledge possessed, magnitude of effort required to codify knowledge, how quickly constructed, performances, and return on investment. On basis of comparison, concludes Al most successful when applied to well-formulated problems solved by classifying or selecting preenumerated solutions. In contrast, application of Al to poorly understood or poorly formulated problems generally results in long development time and large investment of effort, with no guarantee of success.

Vogel, Alison Andrews↗

NASA NTRS1991

Semiautomatic Design Of Zonal Computational Grids

EZGrid is knowledge-based computer program semiautomatically generating zonal computational grids for use in numerical simulations of two-dimensional flows. Zoning necessary because of limitations imposed by size of available computer memory and by topological complexity of typical flow field. Complexity and amount of required memory reduced by dividing flow field into zones, within each of which computational grid refined only to extent necessary to resolve local high gradients. Developed to speed and systematize zoning.

Vogel, Alison Andrews↗

NASA NTRS1990

Automated domain decomposition for computational fluid dynamics

Automation of flow-field zoning in two-dimensions is an important step towards easing the three-dimensional grid generation bottleneck in computational fluid dynamics. A knowledge-based approach works well, but several aspects of flow-field zoning make the use of such an approach challenging. A proposed model and language to describe the process of zoning a flow field are presented, followed by a discussion of the implementation of EZGrid, a knowledge-based two-dimensional (2-D) flow-field zoner. Results are shown for representative two-dimensional aerodynamic configurations. Finally, an approach to the evaluation of flow-field zonings is described and used to compare the performance of EZGrid with that of a human expert.

Vogel, Alison Andrews↗

NASA NTRS1989

A knowledge-based approach to automated flow-field zoning for computational fluid dynamics

An automated three-dimensional zonal grid generation capability for computational fluid dynamics is shown through the development of a demonstration computer program capable of automatically zoning the flow field of representative two-dimensional (2-D) aerodynamic configurations. The applicability of a knowledge-based programming approach to the domain of flow-field zoning is examined. Several aspects of flow-field zoning make the application of knowledge-based techniques challenging: the need for perceptual information, the role of individual bias in the design and evaluation of zonings, and the fact that the zoning process is modeled as a constructive, design-type task (for which there are relatively few examples of successful knowledge-based systems in any domain). Engineering solutions to the problems arising from these aspects are developed, and a demonstration system is implemented which can design, generate, and output flow-field zonings for representative 2-D aerodynamic configurations.

Vogel, Alison Andrews↗