Viscous Hydrodynamic Forces and Ship Velocity: An Analysis

[wssrwsmt]

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　？

 

[SteamKing]

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　？

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.

 

[wssrwsmt]

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.

Thanks for your answer.