This Special Issue presents a set of papers presented to the special session "design generation and evolution of flow systems" of the 7-th International Conference on Diffusion in Solids and Liquids - DSL2011

Natural and engineered flow systems have an intrinsic beauty visible for everybody. They are not amorphous – they have configurations (designs). Concepts and principles of fluid dynamics and heat transfer are fundamental to describe these systems. The ability to understand and predict things is related intimately to the scientific process. From the very early days where some basic ideas in fluid motion were introduced (complex flows over objects in streams were observed and sketches drawn by Leonardo da Vinci (1452 – 1519)), to the essential contribution of Newton’s Book II of Principia Mathematica (1687), where a mathematical formulation of fluid flow started to take shape, and to the present it has been a long and fruitful journey. Efforts to improve the theoretical understanding (analytic theory) and experimentation are still taking shape. Numerical simulation (computation) provides a definitive tool that can be used to provide high-fidelity computer-based observations of the phenomena. All these efforts are generating many opportunities to develop new avenues of research