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How to determine characteristic length?

  1. Mar 10, 2016 #1
    There are characteristic lengths for Reynold's, Grashof, Nusselt, and Biot number but the method of obtaining them is not given in my notes. I would like to know how to do so for a plane wall, cylinder and sphere. Thank you.
     
  2. jcsd
  3. Mar 10, 2016 #2
    Have you tried a search, and see to where that leads.
    https://en.wikipedia.org/wiki/Reynolds_number
    https://en.wikipedia.org/wiki/Biot_number
    https://en.wikipedia.org/wiki/Nusselt_number
    etc. as a starter.

    A pipe, for example, would have a Reynold's characteristic length of its diameter.
     
  4. Mar 11, 2016 #3
    The biot number characteristic length is volume/(eternl surface).
    For convention problems the characteristic lengths are in according to the correlation u are using. Normaly They are the Most intuitive ones. I suggest you to look for the incropera textbook. U can find the pdf version easily searching on Google.
     
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