This book presents select proceedings of the International Conference on Advances in Fluid Flow and Thermal Sciences (ICAFFTS 2021) and summarizes the modern research practices in fluid dynamics and fluid power. The content of the book involves advanced topics on turbulence, droplet deposition, oscillating flows, wave breaking, spray structure and its atomization and flow patterns in mini and micro channels. Technological concerns relevant to erosion of steam turbine blade due to droplets, influence of baffle cut and baffle pitch on flow regime, bubble formation and propagation in pool boiling, design optimization of flow regulating valves are included in the book. In addition, recent trends in small-scale hydropower plant and flow stability issues in nanofluids, solar water heating systems and closed-loop pulsating heat pipes are discussed. Special topics on airflow pattern in railway coach and vortex tube are also included. This book will be a reliable reference for academicians,researchers and professionals working in the areas of fluid dynamics and fluid power.