Air flow is a ubiquitous phenomenon and is generated under the influences of various objects and phenomena on earth. In this project, we explored interaction methods using a visualization method of the flow field in case studies. A background-oriented schlieren (BOS) method, which visualizes the density field of the flow, was used in this study. Visualizing the air flow around a human body or object demonstrated the ability to provide meaningful information about the target person or object. In addition, by prototyping and testing systems, we discussed the use of the visualized flow to sense the fine airflow and the use of the flow as an input interface.