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March 16, 2009, 04:34 |
Select Vertex-Average or Area-weighted ?
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#1 |
New Member
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Hi, everbody. I have a question about the post-handling results. For example, if I have defined a variable in "Custom Field Funtions" like heat transfer coefficient: h=flux/(Temperature-300), now I wanna check the averaged h on a wall surface. In pannel [Reports-->Surface Integrals], which Report-Type I should select:"Area-weighted " or "Vertex-Average " ? The results by the two types are much different !! i.e., 2000 and 100.
BTW: If I select "Vertex-Average" in Field-Variable [custom-field-function], or, I select "Area-weighted" in Field-Variable[Wall-Flux-->Surf.Heat.Trans.Coeff] , the results are similar. i.e., 100 and 120. SO, based on these, I think, Vertex-average is best for custom-field-cuntion varibale. Right? or not. Please give me some suggestions. Thanks |
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March 16, 2009, 05:58 |
Area-weighted
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#2 |
Member
Ralf Schmidt
Join Date: Mar 2009
Location: Austria
Posts: 67
Rep Power: 17 |
Hi!
Vertex-Average gives you the average value related on every vertex. So, if your mesh is not uniform, you end up having over- / underestimated values (e.g. having a high number of cells in regions with high / low values). So, area weighted average is the best choice! I think, the problem in your area-weighted average is, how the area is calculated. If you have a 2D case, the area weighted average might be calculated using the reference area (>report>reference values). Best wishes! Ralf
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CFD - nothing but Colourful Fluid Dynamics |
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March 16, 2009, 08:37 |
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#3 | |
New Member
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I would say that before I use "Area-weighted" to calculate"Wall-flux-->surf heat transf coeff.", I have set the area value (>report>reference values). NOTE that: actually, heat transfer coefficient is indenpendent of area !
whatever the area value I set in reference vaules pannel, The result are similar to that by "Vertex-average" for custom field vaiable why? Quote:
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