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-   -   Reynolds Number Outside the Range ?? (http://www.cfd-online.com/Forums/cfx/22899-reynolds-number-outside-range.html)

Manu July 28, 2006 10:50

Reynolds Number Outside the Range ??
 
Hi I ve two queries: 1) i am setting the reynolds number for a backward facing step flow with 3D geometry in CFX.When i am reaching above Re =1000 a warning is coming " Reynold Number is outside the range specified ".It is obvious that i am selecting a Laminar Model in Pre.I exactly dont understand is this error message has to do something with my solution or its just a warning. I am not getting this message in 2D Simulation. 2)

Warning comes after 4-5 iteration "a wall has been placed at the outlet boundary , consider opening b c ....." After appearing 2-3 times it disappears.Than solution converge smoothly.

Why it shows this message ?? What it haas to do with solution?? I ve checked all the grids in ICEM.

-Manu


johnny August 7, 2006 12:39

Re: Reynolds Number Outside the Range ??
 
Error 1 is telling you the Reynolds number is high, and that you should probably be running with a turbulence model. The Reynolds number will be different for your 2d and 3d cases since CFX uses the average length scale (cubed root of volume) for calculating Reynolds number, not the proper characteristic length. You should check to see if running laminar is sensible for your case.

Error 2 is not a problem. If you get final convergence with a wall at the outlet, you may want to consider moving your outlet further downstream.


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