5.5 Modelling

Computer modelling is the simulation of real life processes by computer. In some cases, the rules governing the process may be known; in other cases, the rules may be heuristics based on experience. Examples of computer modelling abound:

• weather forecasting and economic `forecasting': here, modelling is being used to try to gain insight into what will happen or what might happen under certain circumstances;
• stress testing used in CAD and modelling of flow processes in oil wells (for example, water is injected under high pressure into oil wells to force out the dregs of the oil): here, computer modelling is used primarily for economic reasons -- in the first case, it may be cheaper and faster than other development procedures and in the second case, it is being used to try to optimize returns on a costly procedure which cannot be tried beforehand;
• modelling of core activity under various situations in nuclear reactors: the results of the experiments are important for developing emergency procedures, but it would be too dangerous and too expensive to try the experiments in real life;
• modelling of sub-nuclear processes based on theoretical physics: here, a physical model has been proposed and the computer is used to derive the consequences of that model, so that they can be compared with the results of experiments to assess the models validity.