[CfdUser5855]

Hi all,

I ran a simulation using atmBoundaryLayer to prescribe a log law boundary condition to my inlet conditions over a dune field.

However, when I compared the actual output data from a larger scale model which I used to inform my CFD, it does not perfectly follow the log law for boundary conditions and therefore I need to re run a simulation, giving specific heights certain velocities.

I now want to try and have an inlet condition which is : (heights are given as above the STL surface)

11.65 ms at 5.00 m
13.94 ms at 15.00 m
14.96 ms at 27.00 m
15.7 ms at 40.00 m
16.35 ms at 55.00 m
16.9 ms at 72.00 m
17.31 ms at 91.00 m
17.96 ms at 112.00 m
18.46 ms at 135.00 m
18.97 ms at 161.00 m
19.48 ms at 191.00 m
20.01 ms at 223.00 m
20.54 ms at 260.00 m
21.03 ms at 302.00 m
21.47 ms at 348.00 m
21.85 ms at 400.00 m
22.13 ms at 457.00 m

My blockMesh file is shown below:

convertToMeters 1;

vertices
(
(0 518200 0)
(2150 518200 0)
(2150 519270 0)
(0 519270 0)
(0 518200 475)
(2150 518200 475)
(2150 519270 475)
(0 519270 475)

);

blocks
(
hex (0 1 2 3 4 5 6 7) (40 15 10) simpleGrading (1 1 1)
);

edges
(
);

boundary
(
outlet
{
type patch;
faces
(
(0 4 7 3)
(1 5 4 0)
);
}

inlet
{
type patch;
faces
(
(2 6 5 1)
( 3 7 6 2 )
);
}
DuneField
{
type wall;
faces
(
(0 3 2 1)
);
}
top
{
type patch;
faces
(
(4 5 6 7)
);
}
);

I have looked at using TimeVaryingMappedFixedValue but that doesn't seem to be the right thing for this application

It seems like it should be relatively easy but I am unsure how to run the case

Any help would be greatly appreciated

[JulioPieri]

If those numbers come from a function, you could implement it in the source code for the atmBoundaryLayer BC. It isn't that scary, you could go to the same file, make a copy of it and (probably) edit this part:

scalarField Un
    (
        (Ustar(z0)/kappa_)*log(((zDir() & pCf) - groundMin - d + z0)/z0)
    );

and place your function. There are plenty of tutorials on how to create custom BC. Here are some:
https://www.dam.brown.edu/people/ntrask/CFD/bctut.pdf
Custom Boundary Condition with OpenFOAM

As an alternative, check out swak4Foam, it's pretty straightforward to use and might be good.
Also, there is the "codedFixedValue" BC, but I haven't used it yet.

Edit: I think with codedBC would be good. I haven't tested it, but a good starting point could be, in your U file,:

boundaryField
{
youAtmInletPatchName 
{
type    codedFixedValue;
value   uniform 0;
name    codedPatchBC;

code
#{
const vectorField& faceCenter = this->patch().Cf();
vectorField& windVelocity = *this;
forAll(faceCenter, i)
{
windVelocity[i].x() = YOUR FUNCTION HERE;
// then zero in other coordinates
}
#};
}
rest of you patches BC
}

I haven't tested this! It's just a starting point for you.

Hope some of these help