heat transfer coefficients with "bad" yplus

Andrew

Hello,

Has anyone done a SYSTEMATIC investigation of predicted heat transfer coefficients when yplus is out of the suggested ranges? (And more importantly, is willing to talk about it!)

Years ago I (carefully) did a flat plate benchmark and found my commercial code matched the DB correlation well. However, that model was carefully done - two layer, enough cells in the sublayer, hod.

What I wish I had was that data, and then the following cases also:

Half as many points in the sub-layer 1/10 as many points in the sub-layer 2 points in the sub-layer etc.

cases without two-layer model: non-two layer with yplus of 1 non-two layer with ylpus of 10 non-two layer with yplus of 30 (typical minimum of where it is supposed to be) non-two layer with yplus of 100 non-two layer with yplus of 200 non-two layer with yplus of 300 (typical maximum of where it is supposed to be) non-two layer with yplus of 500 non-two layer with yplus of 1000 etc.

What happens to all of the above cases when you run the various differencing schemes? How important is is to use variable fluid properties? What happens when you run other turbulence models?

I know my code works well when you do everything you are supposed to do to get heat transfer coefficients correct, but I don't know how far the code is off if you don't do what you need to do. This information would be useful for evaluating models where wall heat transfer has been included, but not in the detail it should have. (Do my h's change by 10% for a high yplus, or is it 3000%? etc.)

Thanks

Andrew