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Old   August 19, 2007, 14:06
Default Enhanced Wall Treatment
  #1
Phil
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Hello,

I'm having a problem when using a 2nd order scheme with enhanced wall treatment. The soultion deiverges until it crashes completely every time.

Has anyone experienced this before?

Any help is very much appreciated.

Thanks
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Old   August 19, 2007, 14:17
Default Re: Enhanced Wall Treatment
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AAA
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Hi

What is the y+ for the first near-wall grid? Are you trying to model natual convection?
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Old   August 19, 2007, 14:33
Default Re: Enhanced Wall Treatment
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Phil
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I'm unsure what the y+ value is but it looked reasonable.

Not natural convection but a gas turbine combustor model. I get this problem even when using only a turbulence model(no heat transfer). Every time I switch on enhanced wall treatment it diverges, with 2nd order sol.

Thanks

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Old   August 20, 2007, 06:17
Default Re: Enhanced Wall Treatment
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Joe
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What turbulence model are you using?

What, precisely, is your typical yplus value? What is your mesh inflation factor near the wall?

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Old   August 20, 2007, 09:21
Default Re: Enhanced Wall Treatment
  #5
maseay
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Joe (and others),

I cant access my case file just now to get the y+ value but I'll get it asap.

I'm using the RSM because it is required for swirling flow. I need this more than enhanced wall treatment.

By inflation factor to you mean how much the density increases as I move away from the wall? The growth is 1.1 for 6 rows then it goes to a normal mesh.

When I put on enhanced wall treatment and only calculate the turbulence, the nturbulent viscosity is limited in cells but it eventually irons out and starts to converge. As soon as I solve all equations it crashes again. This has occured with various different grids for the same geometry.

As soon as I go into work I'll check the y+ value for 2nd order without EWT, but my laptop is currently in PC World being repaired.

Thanks very much

Phil
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