Thermal fluid properties such as heat transfer and fluid drag are greatly influenced by micro- and nano-scale structures and materials. For instance, it is known that heat transfer efficiency is improved by using microfabricated heat-transfer surfaces, and that ball blurring can be reduced by applying microscopic surface structures. Also, it is known that mixing nanoscale particles in a fluid or confining it in a nanoscale space changes its viscosity and the temperature of phase changes. The main objective of our research is to elucidate the effects and mechanisms of these microscopic properties on the macroscopic properties of fluids, and to apply the findings to the development of highly efficient energy technology.