Question about direction of movement of water molecule

[songoku]

Homework Statement

This is not homework. I want to ask about the direction of movement of water molecules at 1:44 from this video

https://www.youtube.com/watch?v=UVcyea3ZH54

Relevant Equations

Newton's 3rd Law

When the boat moves to the left, water molecules below it also move to the left.

Is it correct to say the reason is because of Newton's 3rd law? Water molecules provide friction force to the boat so force on boat by water molecules is to the right. By Newton's 3rd law, there will be force on water molecules by boat in opposite direction so the force on water will be to the left, then water molecules will move in the same direction as the boat.

Thanks

 

[hutchphd]

Your description is pretty good, particularly for small speeds (small compared to what? is a good question). At higher speeds life gets much more complicated because of vortices and turbulence but one step at a time...

 

[songoku]

Your description is pretty good, particularly for small speeds (small compared to what? is a good question). At higher speeds life gets much more complicated because of vortices and turbulence but one step at a time...

I know the formula of Stoke's law
$$F=6 \pi \eta vr$$

Is there a speed limit to apply Stoke's law?

And will turbulence change the direction of motion of water molecules so the water molecules may move to opposite direction (to the right)?

Thanks

 

[hutchphd]

Look up Reynold's number. This depends upon viscosity and speed and size in an interesting and complicated fashion. Not easy stuff.

 

[songoku]

Thank you very much hutchphd