With the force of a giant waterfall, the dam burst,launching a wall of water 18 meters high down the funnel toward Johnstown faster than warnings could be sounded.

VOA: standard.2010.04.26

And if the distance between the wall and the dam was large in comparison to the wavelength then what happens?

如果水槽壁,和屏障之间的距离,大于波长,会导致什么？

麻省理工公开课 - 固态化学导论课程节选