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Relatively small simulation models provide a means to understand the behavior of an isolated part or function of a glass process, or to assess numerical treatments. However, many problems require the mutual interactions of several parts or processes to be considered simultaneously. A good example is a glass melting furnace, in which there exist several flow regimes, multimode heat transfer, physical and chemical reactions, and other related phenomena.

Modeling a glass melting tank provides a means to estimate the effects of many things contemplated by a glass maker. Simulations made with a properly constructed model can, for instance, assist in prescribing or changing the profiles of combustion burners, E‐boost power zones, or bubbler flow rates. Changes in pull rate, insulation thickness or type, added wind cooling to outside walls, and surface treatments to alter emissivity of crown materials are just a few other examples of what can be considered with a furnace model.

The effects of various changes can be measured in different ways, too. The overall rate of energy consumption is often a key performance index (KPI). Other KPIs relate to the glass quality. For example, the distribution of residence times for material passing through the melting furnace is important to its operators because, with the shortest times, the material is least likely to have been fully conditioned and, thus, is most likely to have some sort of imperfection such as seeds or cords (Chapter 1.2). Other effects of interest include the maximum temperatures of various refractories, the shear stresses and other conditions contributing to wear, the position of the batch line, and the strength of the backflow of glass against the batch layer.

Figure 5 Sketch of a glass melting furnace for the production of reinforcement fiber glass.