In recent years it has been recognized that tundishes playa critical role in affecting the quality of the finished steel products. Furthermore, proper tundish design may be even more important in the development of the novel continuous casting pro cesses that are now in varying stages of realizatic)ll. Traditionally, physical modeling has played a key role in tundish design, but the recently evolved computational software packages, the readily accessible computa tional hardware, and, perhaps most important, the growing experience with tackling a broad range of computational fluid flow problems within a metallurgical context have made mathematical modeling an important factor in this field. Our aim in writing this book has been to bring realistic perspectives to tundish design. The main purpose is to provide a good physical understanding of what is happening in tundishes, together with a realistic discussion of topics that are still not quite clear. The process metallurgist active in this field has many tools at his or her disposal, including mathematical modeling, physical modeling, and measure ments on full plant-scale systems. In this monograph we seek to show how these ideas may be combined to provide a good basic understanding and, hence, an attempt at an optimal design."