Viscous hydrodynamic forces increase with the velocity of a ship, impacting its overall resistance. The resistance consists of frictional resistance and residuary (wave-making) resistance. For vessels with a Froude number (Fn) less than 0.1, the residuary resistance can be neglected, but viscous forces remain significant as they contribute to frictional resistance regardless of speed. Understanding these dynamics is crucial for optimizing ship design and performance.
PREREQUISITESNaval architects, marine engineers, and researchers focused on ship design and performance optimization will benefit from this discussion.
wssrwsmt said:The viscous hydrodynamic forces will increase with increase of the velocity of ship？ Can the viscous hydrodynamic forces be neglected if the velocity of ship is small ？
Thanks for your answer.SteamKing said:Not entirely.
The resistance of a vessel is composed of two parts: the frictional resistance and the residuary or wave-making resistance.
For vessels whose Froude number is less than 0.1, the residuary resistance can be neglected.
(The Froude number is a non-dimensional quantity relating the length and speed of a vessel, Fn = (V/gL)1/2)
The viscous forces produce the frictional resistance of a hull and are always present as long as the vessel is in motion, although at diminishing magnitude.