Читать книгу Encyclopedia of Glass Science, Technology, History, and Culture - Группа авторов - Страница 150

Numerical simulations of glass processes are performed in lieu of physical trials, which often involve conditions too harsh to allow measurements, are difficult to control, or are prohibitively expensive. Used as a screening tool, a simulation model can thus allow technologists to avoid several iterations of actual physical trials on an industrial apparatus. Alternatively, simulations can be used to examine phenomena which are too difficult to observe in practice because of the extreme environment of glassmaking. Moreover, numerical simulation allows for fundamental phenomena to be studied, thanks to its capability of identifying and controlling factors that influence the process. Such factors cannot usually be independently modified in the real process, in view of its complexity, and the insights gained from such virtual experiments can be used to guide technology development efforts.

Following the advent of electronic computers in the mid‐twentieth century, these methods were pioneered in the 1960s to deal with glassmaking problems elementary enough to be handled with the simplifying assumptions required by the then limited computing power. Much more complex and realistic 3‐D problems can of course be tackled now as massive increase in this computing power has dramatically changed engineering analysis in general. Concomitant with hardware advances have been significant developments in software, including both computational algorithms and user interfaces. Several commercial offerings of the relevant software are available for glassmaking. Process engineers are encouraged to utilize such tools. Some of these software packages are general purpose, adaptable to a wide range of situations, whereas others serve the glass‐processing industry specifically.

Both general‐purpose and niche‐software products will be used in the example simulations presented in this chapter where the focus will be put on the mathematical techniques used to simulate the two major phenomena involved in glassmaking, namely fluid flow and heat transfer. Mathematical models, formulated from the classical laws of physics, are used to calculate relevant field variables, such as temperature, velocity, stress, etc., within a glass manufacturing process. Modeling results are then interpreted with post‐processing procedures, which are less abstract than ever before, thanks to modern techniques capable of displaying results in a geometrical context. When applied to fluid flow and heat transfer, these techniques are collectively referred to as computational fluid dynamics (CFD).

To review these new methods, we will first summarize the main six steps they successively involve from the definition of the problem of interest to its solution. The various physical phenomena relevant and their mathematical description and computational treatment will then be expounded. Subsequently, a few representative examples of model simulation will be presented to demonstrate the capabilities and the value of modeling to a glass manufacturing enterprise. Finally, a brief section on the importance of managing simulation data will be provided.