[PenPencil]

Hi all,

I am trying to simulate an incompressible and laminar flow about a system. I am varying the angle of attack of the incoming flow. In order to do so, I have created an O-grid (please see the attached figure. The system is centred at the origin, the flow comes from some angle, and the outer flow domain is a large circumference). However, I have not been getting results that agree physically with the literature and I am quite confident that this has to do with my boundary conditions. So I would like to ask: what is the correct input for my boundary conditions?
I have used the following for the 0/U:

FREESTREAM
    {
        type            freestreamVelocity;
        freestreamValue $internalField;
    }

and for 0/p:

FREESTREAM
    {
        type            freestreamPressure;
        freestreamValue $internalField;
    }

By the way, my FREESTREAM patch refers to the entire outer circumference and it is given in the constant/polyMesh/boundary file as:

FREESTREAM
    {
        type            patch;
        physicalType    patch;
        nFaces          656;
        startFace       538976;
    }

For the wall of the bodies I have been using the wall condition.

The contours of vorticity resulting from this setup are given as in the figure from ParaView, which are very weird.


Any help would be greatly appreciated.

[PenPencil]

I would highly appreciate if anyone could give me some input.

[Tobermory]

I can see why you went for an O-grid, but this is far from ideal, for a bunch of reasons. Plus your domain size is rather small - if you are interested in the wake flow, then the boundaries are way too close.

I would suggest extending the domain, adding a box around your O-mesh, and then applying simpler boundaries on your box faces - fixedValue on the upstream faces; inletOutlet on the downstream faces. You can rotate the box around the O-mesh in a "turntable"mesh fashion to get different angles of attack, if you are feeling really brave.

Good luck.