Decay time of waves in a swimming pool

In summary, the conversation discussed an ideal cylindrical pool with water of depth h and diameter d, and a plunger of width w causing standing waves with a single-node Bessel function pattern. The expressions for wave decay time and amplitude were requested, taking into account viscosity and surface tension. The paper provided in response to the request may be useful in finding the decay of the waves caused by viscosity. The relationship between shear rate and (r,w) was also mentioned. The discussion concluded with a mention of nonlinearities affecting the relationship between wave displacement and volume of water, and a request for clarification on the definition of shear rate.
  • #1
avenged*7
11
0
Hello,
Let's say I have an ideal cylindrical pool (rigid, vertical walls) of diameter d, with water of depth h. Take the ratio of d:h to be around 5:1 - 10:1. If I press down on the surface with a plunger of width w, I cause a standing wave resembling a single-node Bessel function, like a vibrating membrane with non-fixed edges. Taking into account the viscosity and surface tension, what are the expressions for (and how are they obtained)
  1. wave decay time
  2. wave amplitude
I've searched all over, but mostly get expressions for the surface heights obtained via slosh analysis and nothing for the decay time of the wave. Thanks!
 
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  • #2
avenged*7 said:
Hello,
Let's say I have an ideal cylindrical pool (rigid, vertical walls) of diameter d, with water of depth h. Take the ratio of d:h to be around 5:1 - 10:1. If I press down on the surface with a plunger of width w, I cause a standing wave resembling a single-node Bessel function, like a vibrating membrane with non-fixed edges. Taking into account the viscosity and surface tension, what are the expressions for (and how are they obtained)
  1. wave decay time
  2. wave amplitude
I've searched all over, but mostly get expressions for the surface heights obtained via slosh analysis and nothing for the decay time of the wave. Thanks!
Maybe the following paper will be useful in finding the decay of the standing surface waves caused by viscosity:-
http://sites.apam.columbia.edu/courses/apph4200x/Behroozi_Viscous Gravity Waves.pdf
As for the height of the wave, I presume the volume of water in a half wave will equal the displacement of the plunger.
 
  • #3
avenged*7 said:
Taking into account the viscosity and surface tension
Can you write shear rate as a function of (r,w)?
 
  • #4
Thanks for responding! Sorry it took so long to respond as I have had to set the project aside for a short time. I'll be working on it here and there as my time permits.

tech99: I haven't had a chance to read the paper in depth, but it looks promising. As for the wave height, I believe that nonlinearities will not permit such a simple relationship between the displacement and water volume, especially near resonance. I say this also because the wave amplitude visibly grows to its maximum after some time of being constantly driven at the resonant frequency. That is, the wave heights differ at the beginning and at resonance while having the same displacement (or so it appears).

Bystander: I am not sure about that. My expertise is not in fluids, so I need to look into exactly how the shear rate is defined. When I figure that out, I will let you know.

Thanks again!
 

Related to Decay time of waves in a swimming pool

1. What factors affect the decay time of waves in a swimming pool?

The decay time of waves in a swimming pool can be affected by various factors such as the size and depth of the pool, the temperature and chemical composition of the water, and the materials used to construct the pool walls and floor. Other factors that can impact the decay time include the frequency and amplitude of the waves, the presence of obstacles in the water, and the air and wind conditions.

2. How does the size of the pool affect the decay time of waves?

The size of the pool plays a significant role in the decay time of waves. In general, larger pools tend to have longer decay times due to the increased distance the waves have to travel before dissipating. However, the shape and depth of the pool can also affect the decay time, as well as the presence of any obstructions.

3. How does the temperature of the water impact the decay time of waves?

The temperature of the water can affect the decay time of waves in a swimming pool. Warmer water tends to have shorter decay times due to its lower viscosity, which allows the waves to travel faster and dissipate quicker. On the other hand, colder water with higher viscosity can result in longer decay times for waves.

4. What role do the materials used to construct the pool play in the decay time of waves?

The materials used to construct the pool can have an impact on the decay time of waves. Pools made of materials with high absorption rates, such as concrete or tile, may have longer decay times as these materials can absorb the energy of the waves. In contrast, pools made of materials with lower absorption rates, such as fiberglass or vinyl, may have shorter decay times.

5. Can the frequency and amplitude of waves affect the decay time in a swimming pool?

Yes, the frequency and amplitude of waves can affect the decay time in a swimming pool. Higher frequency waves have shorter decay times, while lower frequency waves have longer decay times. Similarly, waves with higher amplitudes will dissipate faster than those with lower amplitudes. These factors are important to consider when trying to control the decay time of waves in a swimming pool.

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