Froude number and wave speed

Discussion in 'Hydrodynamics and Aerodynamics' started by Chuck Bodeen, Oct 22, 2013.

  1. Chuck Bodeen
    Joined: Oct 2013
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Panama City Beach, FL

    Chuck Bodeen New Member

    For shallow water, the Froude number is defined as object speed / wave speed
    or V/c where c=sqrt(g d) and d is water depth and g is acceleration of gravity.

    For a boat, Froude number is boat speed / sqrt(g L)
    where L is the waterline length.

    My question is: What is the physical meaning of sqrt(g L)?
    Is this some kind of wave speed?
     
  2. jehardiman
    Joined: Aug 2004
    Posts: 3,762
    Likes: 1,152, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Yes it is related to wave speed (c) where c = sqrt ((g/k) * tanh (k*d)) and where k is wave number (2*pi/wave length) and d is water depth. It has to do with the mass spring of a wave of length L and is required to make the Fn dimensionless. Get out a copy of Oceanographical Engineering by Weigel or Principles of Naval Architecture for a full discussion of the development of Fn and how it is related to the different k's via water depth.
     
Loading...
Similar Threads
  1. Elias1999
    Replies:
    5
    Views:
    1,200
  2. dbharrison1
    Replies:
    3
    Views:
    4,231
  3. gonzo
    Replies:
    23
    Views:
    6,750
  4. PieroF
    Replies:
    2
    Views:
    1,994
  5. deanlife
    Replies:
    11
    Views:
    5,589
  6. Surfer Naval Architect
    Replies:
    4
    Views:
    1,566
  7. sandhammaren05
    Replies:
    417
    Views:
    50,875
  8. revintage
    Replies:
    0
    Views:
    1,461
  9. A.H.Sabahi
    Replies:
    6
    Views:
    2,763
  10. Earl Boebert
    Replies:
    16
    Views:
    4,960
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.