Resonant frequency of a pipe submerged under water

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Discussion Overview

The discussion revolves around calculating the resonant frequency of a pipe that is completely submerged in water. Participants explore the implications of different conditions, such as whether the pipe is open or closed at one end, and the effects of the pipe's material on the acoustic properties.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant suggests using the speed of sound in water (1,481 m/s) divided by the length of the pipe multiplied by 4 to find the resonant frequency, providing a specific example with a 20 cm pipe.
  • Another participant references a Wikipedia article on acoustic resonance and questions the initial participant's doubts.
  • A third participant reiterates the initial question about calculating resonant frequency and notes that for a pipe open at both ends, the formula would differ, requiring half a wavelength instead of a quarter.
  • One participant clarifies that they were considering a pipe closed at one end, which affects the calculation.
  • Another participant raises concerns about the practical implications of the experiment, suggesting that the material of the pipe may significantly influence the behavior of the submerged pipe compared to an air column, and questions the effective length of a PVC pipe under these conditions.

Areas of Agreement / Disagreement

Participants express differing views on the appropriate formula to use based on whether the pipe is open or closed at one end. There is also a lack of consensus regarding the influence of the pipe's material on the resonant frequency.

Contextual Notes

Participants note that the behavior of a submerged pipe may be more complex than simple calculations suggest, with factors such as material properties and internal pressure variations potentially affecting results.

Who May Find This Useful

This discussion may be of interest to those studying acoustics, fluid dynamics, or engineering, particularly in contexts involving submerged structures and resonant frequencies.

supak111
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How do I calculate a resonate frequency of a length of pipe submerged totally under water?

Do I just take speed of sound in water which is 1,481m/s at room temp, and decided it by length of pipe in meters multiplied by 4?

so at 20 celsius water and 20cm pipe it would just be: 1481 / (.2 x 4) = 1851.25Hz??
 
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supak111 said:
How do I calculate a resonate frequency of a length of pipe submerged totally under water?

Do I just take speed of sound in water which is 1,481m/s at room temp, and decided it by length of pipe in meters multiplied by 4?

so at 20 celsius water and 20cm pipe it would just be: 1481 / (.2 x 4) = 1851.25Hz??
Remember that if the pipe is open at both ends then it needs to be half a wavelength long rather than a quarter.
 
The formula given is for a half open pipe
 
Thanks everyone, yes I was wondering about a pipe that's closed on one end, forgot to specify.
 
If the 'experiment' relates to some system for the measurement of pipe length then it may not be as simple as that.
On a practical level, the behaviour of a pipe full of water might be more affected by the material of the pipe than the air column that the model . The modulus of water is very high, compared with air so I wonder what the effective length of a PVC pipe might be. The pipe with water in it is likely to flex due to internal pressure variations and interact much more than for an air column in the same pipe (that's in addition to the different inherent wave speed).
 
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