will the motion of water in which the wave propagate change the frequency of wave

gstar2002

i know that motion of source can change the frequency of wave.
constant speed motion will not change the wave progagation relative to water itself.but from the point of a observer at speed 0, the propagation speed will change. so my question is what will happen to frequency?
thanks for help. maybe the motion is then not wave.

hikaru1221

Suppose that the source doesn't move. In T, the source emits a full wavelength d = vT, where v is the propagation speed in moving medium. The wave front approaches the observer with speed v. So to pass the observer a distance d (= 1 wavelength), it takes time = d/v = T. So nothing changes The result is not surprising, as Doppler effect has nothing to do with propagation speed in the medium.