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-   -   Off drag coefficient (http://www.cfd-online.com/Forums/star-ccm/113513-off-drag-coefficient.html)

jackwabbit February 21, 2013 01:15

Off drag coefficient
 
Yes, hello, I'm currently working on the numerical analysis of flow around an Ahmed body with a rear slant angle of 35 using Star ccm+. I'm getting a value of 1 for the total drag coefficient when the validated value is around 0.25. I've more or less checked everything so I'm going to go with a error in the mesh. If it's the mesh or not the mesh, any suggestions on what could be the problem?

siara817 February 21, 2013 06:33

You can refine the mesh and check the value of drag coefficient. The mesh must be improved until you the drag coefficient become constant.

jackwabbit February 21, 2013 07:02

Oh alright, thank you! The force coefficient does become a constant does become constant but just at the wrong value. And yes, I'll work on refining the mesh. Are there any recommended range of values for the mesh size for this case? Since the Ahmed body analysis is a pretty standard one.

siara817 February 22, 2013 03:38

As you said at your first post, the drag coefficient should be around 0.25. Do you use k-omeg?

jackwabbit February 22, 2013 08:19

Nope. I've been using K-epsilon till now, will try k omega and get back. Which model would you say would be appropriate: the standard model or the SST one?


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