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What does it by parametric instability?

  1. Mar 14, 2015 #1

    I'm majoring in fluid mechanics. I notice some researchers are using the phrase parametric instability. I googled it, it seems this comes from the solid mechanics (vibration). Can you explain to me what's the difference between parametric instability and the resonance? They seem the same thing to me according to the explanations I found on web.

  2. jcsd
  3. Mar 14, 2015 #2


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    Parametric stability has a wider use than you are thinking. Suppose you are working on an engineering problem. If you know the exact parameter values of the problem, and you know that they will never change at all, then you can solve the problem. But what if those parameters change a little? Will your answers change a little, or will the answers change completely? Will the system become unstable? Parametric stability addresses the question of how sensitive your answers are to the parameters of the problem.

    P.S. You will probably never have a real-world problem where you know the exact parameters and can say that they will never change.
  4. Mar 14, 2015 #3


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    More broadly it has to do with the fact that rather than changing the details of the driving force behind an oscillation, you are changing some physical parameter in the system and its response to the forcing then changes. I don't know how the research in question is using the concept in fluid mechanics, but that's the general idea. It's not just used for sensitivity analyses of different parameters, but is sometimes an integral part of how a device functions.
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