drag coefficient is so small
 

the drag coeff. of 2d circular tube is about 1 in the literature.
but my obtained result is about 0.01
reynolds number is about 600
k omega model and enhanced wall treatment is used

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Have you found out why? I seem to have the same problem. I am simulating the flow past a cylinder, and find out the drag coefficient is an order of magnitude lower than what in the textbook when Re is around 100.

Thanks,
Philer