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April 26, 2013, 04:25 |
wiggling in the Cd value
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#1 |
Senior Member
Join Date: Jan 2013
Posts: 134
Rep Power: 13 |
Dear all,
I am simulating a 2D kepsilon case of flow around cylinder, Re=100. A rough look at the drag coefficient plot looks good. But when I zoom in, it seems there are two parallel lines forming the plot, and the value of Cd is wiggling in a small range. any idea why? |
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June 16, 2013, 12:02 |
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#2 |
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
Posts: 10,975
Blog Entries: 45
Rep Power: 128 |
Hi Kai,
Since you mentioned this thread on your other thread: http://www.cfd-online.com/Forums/ope...les-cd-cl.html - here's what I can figure out: The mesh is very likely to have the exact size, plus the "deltaT" ahve the right value, for this phenomenon to occur. This has to do with the effect of discretization... for which I can never find a good example on the web But imagine the following scenario: you have a plot of a sine with a period of 1 second and amplitude of 1.
Best regards, Bruno
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