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-   -   Taylor microscale (http://www.cfd-online.com/Forums/openfoam/109427-taylor-microscale.html)

anishtain4 November 17, 2012 06:19

Taylor microscale
 
has anyone calculated taylor microscale in openfoam?
Appreciate it if you share the code.

anishtain4 November 20, 2012 06:33

any one has any Idea?

chegdan November 20, 2012 12:16

People might be more likely to help if you provide a little more information e.g. equations; sources; what you have tried already; what type of simulation your are performing. I'm interested in the topic if you can provide more details.

anishtain4 December 7, 2012 05:28

thanks for the interest chegdan,
Taylor microscale is the main length scale measured in turbulent homogeneous box to determine Reynolds number since there is no physical length scale. here is a more descriptive of what it naturally is:
http://en.wikipedia.org/wiki/Taylor_microscale
but a formula to calculate it is presented in "turbulent flow" by Pope in page 199.
Can you tell me how to put that formula in Opefoam?

chegdan December 10, 2012 14:50

Looking at Pope, around the page that you suggested, I find that the longitudinal Taylor microscale \lambda_f(t) can be related to the transverse Taylor microscale \lambda_g(t) via
\lambda_f(t) = \sqrt{2}\lambda_g(t)
where
\lambda_g = \frac{k^{\frac{3}{2}}}{\epsilon}\sqrt{\frac{10\epsilon\nu}{k^2}}
However, this formulation seems simplistic compared to the definition by pope using the longitudinal (f(r,t)) and transverse (g(r,t)) autocorrelation functions. If you are looking for those, then I will have to think about this some more.

If you are satisfied with the second equation formulation, then I would suggest you look into the post-processing utilities as to how variables are read in at each time and used to calculate what you want e.g. Co utility. Give it a try and post back if you run into problems.


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