Calculating Water Pressure from Speed: A Scientific Approach

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SUMMARY

This discussion focuses on calculating the pressure exerted by water based on its speed using Bernoulli's principle. The key formula presented is P = 1/2ρv², where P represents dynamic pressure, ρ is the density of the fluid, and v is the velocity of the water. The conversation emphasizes the importance of using consistent units, particularly converting water speed from knots to feet per second and density to slugs per cubic foot for accurate pressure calculations. The example provided involves a water speed of 6 knots and a plate area of 3 square feet, illustrating practical applications of the formula.

PREREQUISITES
  • Understanding of Bernoulli's principle
  • Knowledge of fluid density and its units
  • Ability to convert velocity units (knots to feet per second)
  • Familiarity with pressure units (psi and psf)
NEXT STEPS
  • Research the application of Bernoulli's principle in fluid dynamics
  • Learn about unit conversions for fluid mechanics
  • Explore the concept of dynamic pressure in incompressible fluids
  • Study examples of pressure calculations for various fluid flow scenarios
USEFUL FOR

This discussion is beneficial for engineers, physicists, and students studying fluid dynamics, as well as anyone involved in calculating fluid pressure in practical applications.

zeroonezero
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How do you calculate the pressure exerted by water if you know the speed?
 
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Its difficult to say without knowing more, but you might try

http://en.wikipedia.org/wiki/Bernoulli%27s_principle"
 
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What I really should have asked was: Since I calculate the pressure applied by a given wind speed by the following simple method:- Mph^2 * 0.0027 = psf so, is there a simple method to calculate the pressure applied by a given water speed? Thanks
 
If all you want to know is the dynamic pressure, then you can find it for any incompressible fluid (which includes most gases, so long as the speed in question is below about mach 0.3) by simply using the equation P = 1/2ρv2.
 
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Pardon my ignorance...the only thing I know is the speed of the water...6 knots...I have a plate 3ft sq facing that flow...How do I calculate the pressure on that plate, or any plate, in terms of psi or psf? P=1/2pv2 does not make sense to me since P, p is pressure
 
cjl said:
If all you want to know is the dynamic pressure, then you can find it for any incompressible fluid (which includes most gases, so long as the speed in question is below about mach 0.3) by simply using the equation P = 1/2ρv2.

In the formula above, the stagnation pressure P is a function of the density of the water (little p) and the velocity of the water. What you have to do is convert the velocity of the water from knots to units you can use with density in order to calculate the pressure P. If you use velocity in feet per second, for example, the density of the water must be in slugs per cubic foot. The resulting pressure will be in pounds per square foot.
 
zeroonezero said:
Pardon my ignorance...the only thing I know is the speed of the water...6 knots...I have a plate 3ft sq facing that flow...How do I calculate the pressure on that plate, or any plate, in terms of psi or psf? P=1/2pv2 does not make sense to me since P, p is pressure

In the equation P = 1/2ρv2, the ρ is not a p (see the difference?). It's a greek letter rho, which is the density of the fluid. As SteamKing said, you'll need to use consistent units in order for the answer to be correct.
 
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Oops! Did not catch that...Thanks...
 

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