Now, it may so happen that in a well designed stern you cannot avoid variation of velocity in
this direction, there will be a variation of velocity in this direction. Imagine the ship, the
sections are very thin here, at this portion, the stern- if you remember the stern- the section
goes like this and expands out. Lingra, the ship is full, a little forward of the aft, and suddenly
closes in and then expands here. So, the geometry in this portion is very complicated, very
highly three dimensional. So, when you allowing the water to flow past it, it is having a axial
direction of flow that way, a vertical direction and also a it is closing in, so a transverse
direction- there is three directions of flow, all x y and z directions, can you understand that