And if you had a motor here that was causing a paddle to move up and down you could cause waves to form at one end of the tank and move from left to right.

如果在水槽里放个发动器,来让水上下起伏,波浪形成于,水槽的一端,然后从左向右扩散。

麻省理工公开课 - 固态化学导论课程节选