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Old   April 15, 2007, 12:50
Default SST Model
  #1
Sze Hong
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Hello, I was just wandering if somebody could explain to me what exactly does the sst turbulence model do and what are the advantages and disadvantages. Ive tried reading the help files but There are only equations and something abount relationships with other kinds of modelling. Thanks
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Old   April 16, 2007, 04:48
Default Re: SST Model
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Zurayk
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Hello Hong, I worked some time ago with this model, and found that I have some Information about it, hope it may help.

the SST model solves the k-E turbulence model in the bulk flow, and the k-w model at the wall. the SST model is very accurate in catching separations in Low Reynolds flows, on the other hand it under predicts convective heat transfer in flows that are under strongly favorable pressure gradient.

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Old   April 16, 2007, 06:14
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Omer
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Apart from what Zurayk says, make sure that the Y+ is less than 2. This is what everyone recommends, to resolve the boundary layer properly, eventhough CFX can pretty much automatically choose what kind of approximation to use at the boundary, depending on your Y+.
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Old   April 16, 2007, 08:23
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Sze Hong
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What do you mean by the Y+ Im running the simulation at M=0.7 and the RE is approx 6,000,000 so basically the SST model is not the best model to work with right?

Thanks
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Old   April 17, 2007, 10:39
Default Re: SST Model
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Omer
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Y+ would specify ( non-dimensionally) how far your first node is from the wall. It would be a good idea to have it below 2, when you are using SST for properly resolving the boundary layer.

You cannont say, if SST model is best or not, from the little information you provide. I guess you need to look into literature related to problems like yours, to decide.

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