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March 19, 2013, 11:06 |
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#21 | |
Senior Member
Lefteris
Join Date: Oct 2011
Location: UK
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Quote:
(http://www.engineeringtoolbox.com/wa...ity-d_596.html) Another thing that I always ensure is to scale the grid. For example, if you have created the grid with the dimensions in mm, then before running your simulation you should convert your grid's dimensions from mm to m.
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April 11, 2013, 05:53 |
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#22 |
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Osman
Join Date: Oct 2012
Location: Japan
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The recirculation length L/D at Re=40 is around 2, however, from literature i found that it is in the range 2.2~2.4.
Could you please tell me what could be the reason?? (I used different grid size, however i got the same results) In addition, i am using Tecplot to calculate the drag coefficient. For example: If the Cylinder radius is for example R=0.05 & the grid size is dx=0.01 I could not get accurate results for the drag coefficient if the the calculation is taking place with the same radious. But, i get accurate results for the drag coefficient if i used a radious smaller than the actual radious such as R=0.0485. What could be the reason???? |
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April 28, 2013, 08:32 |
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#23 | |
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Lefteris
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I would use much smaller grid spacing. dx=0.01 is too large I think compared to diameter of the cylinder.
Quote:
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April 28, 2013, 09:33 |
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#24 |
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Osman
Join Date: Oct 2012
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Thanks a lot for your reply.
what about the 2nd half of my question about tecplot!! i am using Tecplot to calculate the drag coefficient. For example: If the Cylinder radius is for example R=0.05 & the grid size is dx=0.01 I could not get accurate results for the drag coefficient if the the calculation is taking place with the same radious. But, i get accurate results for the drag coefficient if i used a radious bigger than the actual radious such as R=0.055. What could be the reason???? |
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April 28, 2013, 12:27 |
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#25 |
Senior Member
Lefteris
Join Date: Oct 2011
Location: UK
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I don't really get it.
Why don't you just compute in your code the force on the cylinder?
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April 29, 2013, 07:35 |
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#26 |
Member
Osman
Join Date: Oct 2012
Location: Japan
Posts: 53
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Actually, now, i am calculating it in my code (Immersed Boundary Code).
The drag coefficient is excellently matching the reference data at Re=185 However, the lift coefficient is small around 0.302 In reference data it is around 0.42 Do you have any suggestion?? |
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