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what's the difference between the Standard and Rea

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Old   July 7, 2004, 23:33
Default what's the difference between the Standard and Rea
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Lu
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My case is for simulating film cooling, but when I tried those two different models, the results I get differ. But for RNG and standard model. it's almost same. I think for those three turbulent model, it should not have big difference. Any suggestion?
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Old   July 10, 2004, 17:57
Default Re: what's the difference between the Standard and
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AJ
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The mesh requirements for both models could be different.... Some of these turbulent models are sensitive to mesh density compared to others....

AJ
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Old   July 12, 2004, 06:16
Default Re: what's the difference between the Standard and
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Iason Hatzitheodorou
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The Realizable and the RNG k-epsilon model were developed in order to compensate for some of the problems encountered in the standard k-epsilon model (adverse pressure gradients, stagnation point anomaly, separation, swirl and others). In your problem most of these problems are not present and hence the level of agreement is not surprisin. The realisable model is called as such because it imposes a realisability condition on the the eigenvalues of the shear stress tensor in order to determine the maximum allowable turbulent viscosity. Hence it is physically more consistent than the other two models; however both the realizable and the RNG are not as validated as the k-epsilon model, and it is not unusual for them to actually under-perform due to the numerics.

Bottom line is that in your case I would put more faith in the standard and RNG than the realizable case. Meshing requirements are identical for all 3 models.
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