The academic field of study that aims at systematization of ways which deals with not only thinking about chemical reaction processes but also physical reaction process such as flow and mixing of fluid, heat and materials transportation, is referred to as reactive fluid dynamics or reacting flow. Reacting flow can be divided into two categories; one is gas-phase reacting flow and the other is liquid-phase one. The reports of liquid-phase reacting flow is smaller than that of gas-phase reacting flow. The liquid-phase reacting flow is called Chemo-hydrodynamics in Europe and it is a very new field of study that is in 2009 the international meeting was held for the first time on this. Prof. Nagatsu has reported the phenomena called viscous fingering(VF) and controlling flow involving viscosity decrease due to a chemical reaction the first time in the world.