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- - **Apparent inviscid flow over rectangle problems**
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Apparent inviscid flow over rectangle problems1 Attachment(s)
Hi all,
I'm simulating flow over a rectangle at a Reynolds number of 10^5, using upwind discretization scheme, komega turbulent model, water at 20 degrees C as the fluid. I'm expecting to see recirculation just behind the leading edge of the rectangle but I can't see it. Attached is a picture of my stream lines. I'm using a grid set up such that I have a y+ of ~5. From my picture you can see that it looks like my simulation is completely inviscid, which makes no sense to me. Anyone have any ideas? Thanks -J |

Does anyone have an idea for this?
Thanks -J |

If anyone has any ideas for this I would really appreciate it, I am really stuck on this one. I think the issue is with my wall functions, but I really don't know. Here is my 0/nut file:
dimensions [0 2 -1 0 0 0 0]; internalField uniform 0; boundaryField { inlet { type fixedValue; value uniform 0; } outlet { type zeroGradient; } topAndBottom { type symmetryPlane; } rectangle { type nutWallFunction; value uniform 0; } frontAndBack { type empty; } } Does anyone have any ideas to help me out? Thanks -Jeff |

Hi Jeff,
how do you define your rectangle patch in constant/polymesh/boundary? it should be wall. And what about k and omega values? they should be kqRWallFunction and omegaWallFunction. One more check: what OF version are you using? hope it helps. regards mad |

Hi mad,
My rectangle patch is defined as a wall, and I am using the kqRWallFucntion and omegaWallFunction for k and omega respectively. I'm using OF v1.6. Any other thoughts? -J |

Here's another noodle scratcher;
If I plot my wall shear stress at my last time step on the wall (close to the leading edge, x~10% down the wall) I get a value of about 1.8e-5. If however I plot my velocity gradients at the same location, I get a value of 12.5, which if I multiple it by the dynamic viscosity (in this case it's 0.001) I get a wall shear stress value (cause tau_wall = mu * wallGrad) I get a wall shear stress of 0.0125, which doesn't at all match up with 1.8e-5. Can anyone make anything of this? -Jeff |

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