Water wave metamaterials

Water waves are a common kind of wave in our life, which can provide green energy but may also be accompanied by risks. How to control their propagation and reduce their hazards has become an important topic in water wave dynamics. However, traditional methods are simple and not very effective, and since they are not based on clear physical principles, their design is relatively difficult and haphazard. Hence it is particularly important to find more effective methods for their control. In the past decade, transformation optics has developed rapidly and has been used to design metamaterials, which have clear physical mechanisms and can strongly influence an optical field, so recently, there have been several studies on their application to water wave manipulation. This paper will mainly focus on the history of the development of water wave metamaterials based on transformation optics. In particular, we will describe the basic methods and devices to control water waves with metamaterials, which could pave a new way for water wave manipulation and engineering.