Experimental study on microbubble drag reduction on soil-steel interface

The soil-structure interface behavior is an important concern in ocean engineering design. In some cases, it is necessary to reduce the drag of structure, especially the shear stress on the soil-structure interface. In this study, a series of microbubble drag reduction experiments were first carried out on soil-steel interface. The effects of microbubble volume, moisture content, rotation speed and water types (freshwater and seawater) were investigated. It is shown that the average drag reduction ratio ranged from 15% to 92% under various conditions. With the increase of microbubble volume, the drag reduction effect is improved. Meanwhile, the characteristics of drag reduction were also explored under different moisture content. The drag reduction effect of microbubbles is relatively stable at different speeds.Its is proved that the microbubble drag reduction method can obviously reduce the soil-steel interface drag.