Note that for deep water, when the mean depth " h " goes to infinity, the mean Eulerian velocity \ boldsymbol { U } and mean transport velocity \ tilde { \ boldsymbol { U } } become equal.
12.
The observer installs a row of clocks that either are synchronized a ) by exchanging light signals according to the Poincar?Einstein synchronization, or b ) by " slow clock transport ", that is, one clock is transported along the row of clocks in the limit of vanishing transport velocity.
