辛辛苦苦回了个贴，居然一刷百度贴吧我的回帖就没了。
这题本质上是一个振动和波的题，今年的题目难度变大了，这题的物理基础是2014年的一篇nature physics文章，文章题目是Generation and reversal of surface flows by propagating waves。文章主要讨论表面涡旋surface vertices。另外提醒一下，这题的实验难度和理论难度属于这次题目中最高的题目之一
文章摘要：The ability to send a wave to fetch an object from a distance
would find a broad range of applications. Quasi-standing
Faraday waves on water create horizontal vortices1,2, yet
it is not known whether propagating waves can generate
large-scale flows—small-amplitude irrotational waves only
push particles in the direction of propagation3–5. Here we show
that when waves become three-dimensional as a result of the
modulation instability, a floater can be forced to move towards
the wave source. The mechanism for this is the generation of
surface vortices by waves propagating away from vertically
oscillating plungers.Weintroduceanewconceptualframework
for understanding wave-driven flows, which enables us to
engineer inward and outward surface jets, stationary vortices,
and other complex flows. The results form a new basis for
the remote manipulation of objects on fluid surfaces and
for a better understanding of the motion of floaters in the
ocean, the generation of wave-driven jets, and the formation
of Lagrangian coherent structures.