Some questions of scale in simulation, and a few answers

Discusses areas in which the scale of objects and events may drive design choices regarding the model or simulation system to be built. Spatial considerations encompass both the geometric scale of the system and the desired resolution of information. For modeling of electromagnetic phenomena, the scale for adequate resolution will usually include a resolution cell or pixel size. With each determination of spatial scale, there is a correlated determination of temporal increment or resolution. Pixel size and resolution cell size are both related to time-based measures of the electromagnetic system, pulse length and frequency, for instance. The physics (or algorithms) of the system must also be analyzed for relevance based on a spatial and/or temporal scale. An example from computational fluid dynamics demonstrates that, for a given geometry and subject of interest, some effects will be negligible, while others will dominate. The author provides some considerations in answering the following questions: (1) What are the technological limits of scale in various parts of the system? (2) How does one validate the quality of the output of a simulation system?.<>