Covering the latest developments in the field of drag reduction (DR) by surfactant additives, this book explains the types of additives used, the mechanisms by which DR is achieved and the experimental and numerical techniques needed to understand the topic. Based on the authors state-of-the-art research, it firstly introduces readers to the background of turbulent drag reduction and fundamental issues surrounding drag reduction and heat transfer reduction. The book then goes on to provide key information on turbulent drag reduction by surfactant additives, covering experimental studies using laser techniques (LDV and PIV) and direct numerical simulations (DNS), with special treatments of constitutive equations for viscoelastic fluid and numerical simulation algorithms. Brownian dynamic simulations (BDS) of the rheological properties of surfactant solutions, with a consideration of microstructures in the fluid, field tests and other issues associated with practical applications, are also explained.   Each section is structured to move from theoretical background to research results to enable readers to apply the techniques presented to a variety of industrial and scientific areas. These include: energy saving in long-distance or closed-loop circulatory liquid transportation systems, reducing the skin-friction of maritime navigators and developing novel numerical simulation approaches for turbulent flow or rheology.