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-   -   Great lift coefficients but negative drag coefficient?! (http://www.cfd-online.com/Forums/fluent/94863-great-lift-coefficients-but-negative-drag-coefficient.html)

nez November 28, 2011 14:57

Great lift coefficients but negative drag coefficient?!
 
Hi as the title suggests I am having trouble with my drag coefficients with varying alpha. I am modelling a naca 2412 in 2D using a c-grid style mesh which shows no errors during checks. I am using the coupled solver,Green-guass cell based, PRESTO! pressure, and second order Momentum. I have also changed my relaxation parameters to both .09 to avoid oscillation. I do not understand how I can have such accurate lift coefficients but horrible drag coefficients. Thanks in advance.


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