Introduction

Along with learning about specific aspects of matter transport and its relationship to materials engineering, a course in this subject area is an excellent place to learn about the role of modelling in materials science and engineering. Models are used to develop a better understanding of the processes we are trying to control in order to produce better, more reliable and consistent materials. We usually start with a problem (which is often ill-defined, at least initially) and some data. A model is an attempt to draw general conclusions about the behaviour of the system of interest in a quantitative way which allows us to make predictions about the behaviour of the system. Models invariably require certain assumptions and approximations to be made. Thus the model will be limited both in its precision and in its scope or range of applicability. However, a model can be a powerful tool if used carefully, and all materials engineers should have expertise in how to model materials behaviour.

Consider the problem of predicting weather behaviour. A set of observations of many days might lead to the hypothesis that the weather on any given day in a particular location is correlated to the weather on the previous day. Thus if you predict that the weather tomorrow is going to be the same as the weather today you will be correct say 50% of the time.