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boundary layers in an inviscid flow over a forward step

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Old   February 21, 2015, 06:53
Default boundary layers in an inviscid flow over a forward step
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Divyaprakash
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I am doing an Inviscid analysis of flow over a forward step.

The flow just behind the step becomes subsonic. It looks like a boundary layer. But since the flow is inviscid, there shouldn't be any viscous effect of the wall. Is there any other reason for the subsonic flow. I am using Star CCM+ for the analysis. Can it be due to artificial viscosity?


https://www.dropbox.com/s/og4i5se8hl...iscid.PNG?dl=0
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Old   February 21, 2015, 08:24
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Quote:
Originally Posted by Divyaprakash View Post
I am doing an Inviscid analysis of flow over a forward step.

The flow just behind the step becomes subsonic. It looks like a boundary layer. But since the flow is inviscid, there shouldn't be any viscous effect of the wall. Is there any other reason for the subsonic flow. I am using Star CCM+ for the analysis. Can it be due to artificial viscosity?


https://www.dropbox.com/s/og4i5se8hl...iscid.PNG?dl=0

I see practically a normal shock, consequently is correct to have M<1 behind... I also see a shock layer (how many cells for the shock?) therefore I suppose you have some amount of artificial dissipation that can justify the appearence of the viscous layer.
Have you checked a grid refinement?
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Old   February 21, 2015, 21:37
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Why simulate the flow as inviscid? In the absence of diffusion is there any ad hoc mechanism (model) in your solver - other than the very high probability there is high numerical diffusion - to account for recirculation at the step (corner) and potential separation past it?

Application of inviscid flow should be limited to certain flow conditions/criteria (which generally exclude separation)

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