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June 3, 2017, 16:57 |
CFX vs Fluent convercenge residuals
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#1 |
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Hello all,
I'm doing some comparisons between CFX and Fluent in terms of speed and accuracy. I've done CFX runs where I set the target residuals at 1e-6 (as company methodology). When doing the Fluent runs I've came across that the recommended values were 1e-3... Anyone could explain me why this 3 order magnitude difference, as this has direct impact in the run duration? |
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June 4, 2017, 01:55 |
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#2 | |
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Quang Le Dang
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June 4, 2017, 07:28 |
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#3 |
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Glenn Horrocks
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I suspect CFX and Fluent calculate the residuals by different methods, so the numbers need to be compared with care.
To compare CFX vs Fluent objectively you need to compare a well resolved model in both cases. This means mesh independent, adequate convergence and any other tuneable parameters correctly set. It also means that the same settings are not necessarily the best for both - for instance the mesh which gives mesh independence could well be different in both software. Do not assume the same mesh is suitable for both codes. |
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June 4, 2017, 09:14 |
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#4 | |
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June 4, 2017, 09:23 |
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#5 |
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Yes I suspect the same, so I am asking if anyone can confirm this and have a guideline like "fluent residuals are 10x greater" or something like that.
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June 4, 2017, 11:14 |
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#6 |
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Quang Le Dang
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November 7, 2018, 16:25 |
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#7 | |
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Please correct me if I'm wrong. |
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November 7, 2018, 18:36 |
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#8 |
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Glenn Horrocks
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I don't about know the residuals in Fluent, but for CFX the residuals are calculated by a propriety algorithm which has only a general outline described in the documentation. So it is not possible to compare the exact approach as it is not public.
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