Deriving the Speed of Shallow Wave Formulas

AI Thread Summary
The speed of shallow waves in a tub, defined by the formula speed = √(gravity * depth), can be derived from the Shallow Water Equations, which are a simplified version of the Navier-Stokes equations applicable to small amplitude waves. These equations are mathematically similar to those used in Linear Acoustics. Understanding the derivation requires careful attention to the mathematical principles involved. There is no quick method for this derivation, as highlighted by participants in the discussion. The relationship between wave speed, gravity, and depth is fundamental in fluid dynamics.
ph_low
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for shallow waves (where \lambda \leq 1/2 depth) in a tub, can anyone tell me why...

speed\ of\ wave = \sqrt{gravity * depth}

i mean, is there a way to get this formula by deriving from others?
 
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It can (ofcourse) be derived from the Navier-Stokes equations. See e.g. http://www.ocean.washington.edu/people/faculty/parsons/OCEAN549B/lwt-lect.pdf
 
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ph_low said:
for shallow waves (where \lambda \leq 1/2 depth) in a tub, can anyone tell me why...

speed\ of\ wave = \sqrt{gravity * depth}

i mean, is there a way to get this formula by deriving from others?

That comes from the Shallow Waters Equations. These equations are a version of Navier-Stokes equations for small waves into water whose amplitude is small compared with the height of water itself.

The Shallow Waters Equations are also very similar (mathematically) to the ones of the Linear Acoustics. If you want to know more about that, you will have to pay attention to derivation, as DaWillem has said. I don't know a rapid method.
 
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