[nlc]

Jonathon Sumner Is the one that was working on log treatment at Bottom.




The link for my work at the time is there I did a short resume of part of Sumner work at the time (p. 14).


You can see (p. 19 ) the top BC I use and the reason why. One difficulty of using gradient at the top is that convergence is a lot slower. To fix that I would initialized the hole domain. I did a 1d simulation then initialize the domain with it. I did the same for inlet (use the 1d simulation for the inset).



http://espace.etsmtl.ca/id/eprint/1153/


Hope this help a little.


Bon confinement et n'oubli pas de t'amuser René.



Au plaisir de parler de vive voix un jours.

[Tibo99]

Hi Nic!

Thanks again for your guidance!

I followed the modification that I've seen in your thesis, read some papers including the same one that you pointed me out (Sumner J. & Masson C. k-e simulation of neutral atmospheric boundary layer: analysis....) and I still got this weird curve/shape(two peak) for "k".

The wind profile is not exactly the same also, worst at mid-length then at the Outlet.

I suspect couple of things:

1-Maybe the modification perform in "nutkWallFunction" and "epsilonWallFunction" file are not well done.

2-Maybe the constant Cs (use in "nutkWallFunction") is not right regarding the "z0" I use.

3-Maybe the gradient value I used for "du/dz" and "de/dz" are not right.


I'll keep trying to dig in and looking what go wrong........

Bon confinement aussi!! Héhé! On peut se parler de vive voix certainement et comparer comment vous vivez le confinement dans votre coin! Je vais essayer de te trouver sur FB! :P

Take care!

RT

[HPE]

Might the following be related:

ENH: Improve and verify atmBoundaryLayerInlet conditions including "tutorials/verificationAndValidation/atmosphericFlows/HargreavesWright_2007"

[Teresa Sun]

Dear all,

I use OpenFOAM/v2106-foss-2021a to simulate the wind turbine with pimpleFoam using large-eddy simulation.

The boundary condition for the viscosity at the bottom wall is atmNutUWallFunction.
The inlet BC for velocity is atmBoundaryLayerInletVelocity.

The mean velocity matches experimental data quite well.
However, there is a spike close to the bottom wall in the turbulent kinetic energy profiles and the turbulence intensity. (The green line in the figure is OF results)

Any help would be appreciated.

0.org/U

#include        "include/initialConditions"

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform $flowVelocity;

boundaryField
{
    outlet
    {
        type            inletOutlet;
        inletValue      uniform (0 0 0);
        value           $internalField;
    }

    inlet
    {
        //type            fixedValue;
        //value           $internalField;
        type            atmBoundaryLayerInletVelocity;
        #include        "include/ABLConditions"
    }

    ground
    {
        type            uniformFixedValue;
        value           uniform (0 0 0);
        uniformValue    constant (0 0 0);
    }

    #include "include/sideAndTopPatches"
}

0.org/nut

dimensions      [0 2 -1 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    #include "include/ABLConditions"

    inlet
    {
        type            fixedValue;
        value           $internalField;
    }

    outlet
    {
        type            fixedValue;
        value           $internalField;
    }
    ground
    {
         type            atmNutUWallFunction;
         //type          atmNutkWallFunction;
         boundNut        true;                  ///zero-bounda nut near wall
         z0              $z0;
         value           uniform 0.0;
         #include "include/ABLConditions"
         //Cmu           0.09;
         //kappa         0.41;
         //type            fixedValue;
         //value           uniform 0.0;
    }

    #include "include/sideAndTopPatches"
}

0.org/p

#include        "include/initialConditions"

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform $pressure;

boundaryField
{
    inlet
    {
        type            zeroGradient;
    }

    outlet
    {
        type            fixedValue;
        value    uniform $pressure;
    }

    ground
    {
        type            zeroGradient;
    }

    #include "include/sideAndTopPatches"
}

0.orig/include/ABLConditions

Uref                 2.8;          //Reference mean streamwise flow speed at Zref being used in u* extimations [m/s]
Zref                 0.125;        //Reference height being used in u* estimations[m]
zDir                 (0 0 1);      //Ground-normal direction
flowDir              (1 0 0);      //flow direction
d                    uniform 0.0;  //Displacement height


// I = 1%, u* = 0.1377
z0                   uniform 0.03e-3;

0.orig/include/sideAndTopPatches

top
{
    type slip;
}

"(front|back)"
{
    type cyclic;
}

"proc.*"
{
    type            processor;
}

[Teresa Sun]

According to the merge request https://develop.openfoam.com/Develop...e_requests/354, the bug of value in atmNutUWallFunction and atmNutkWallFunction BC is fixed.
However in my case, the simulation is aborted while running on a single processor if I don't provide the value.

0.org/nut
dimensions      [0 2 -1 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    #include "include/ABLConditions"

    inlet
    {
        type            fixedValue;
        value           $internalField;
    }

    outlet
    {
        type            fixedValue;
        value           $internalField;
    }
    ground
    {
         type            atmNutUWallFunction;
         //type          atmNutkWallFunction;
         boundNut        true;                  ///zero-bounda nut near wall
         z0              $z0;
         //value                 uniform 0.0;
         //Cmu           0.09;
         //kappa         0.41;
         #include "include/ABLConditions"
        //type            fixedValue;
        //value           uniform 0.0;
    }

    #include "include/sideAndTopPatches"
}

--> FOAM FATAL IO ERROR: (openfoam-2106)
Essential entry 'value' missing on patch ground


file: /home/jingsun/input_windTurb/1WTM_25/0/nut.boundaryField.ground at line 38.

    From Foam::fvPatchField<Type>::fvPatchField(const Foam::fvPatch&, const Foam::DimensionedField<Type, Foam::volMesh>&, const Foam::dictionary&, bool) [with Type = double]
    in file /sw/arch/Centos8/EB_production/2021/software/OpenFOAM/v2106-foss-2021a/OpenFOAM-v2106/src/finiteVolume/lnInclude/fvPatchField.C at line 131.

FOAM exiting

#0  Foam::error::printStack(Foam::Ostream&)malloc_consolidate(): unaligned fastbin chunk detected
Aborted (core dumped)

[Teresa Sun]

According to this merge requesthttps://develop.openfoam.com/Develop...e_requests/354, the current ABL boundary conditions are limited to the Neutral-stratified situation.
Does anyone know if these BCs are extended to stable and unstable stratification?

[Tibo99]

Maybe you need to look at SOWFA on github.

[Teresa Sun]

Hi Rene,

Thanks for your reply.
I studied SOWFA for a while but had to give it up.
Because the HPC that I have access to does not support the installation of OpenFOAM6, on which the newest version of SOWFA is implemented. Also, I need to implement my own spatial and time discretization methods and my own large eddy model, which takes a bit of effort but is endurable. I supposed it would be hard to reach for any help once I got stuck in SOWFA.

Please correct me if you think differently

[Tibo99]

Hi,

If you want to developp your own code, its probably the right thing to do.

Personnaly, I'm not skill enough to do something like that, but If you are, go for it.

[nlc]

Indeed it should not be difficult. In our reach group we where many to have modified it. That is 10 years ago still this is not a complexe modification if you know the equation you want to implement.

[MMRC]

Hello Teresa,

Did you solver your ABL? I have simulated some using BC's from openfoam, and also happen that K is not kept equal downwind, but looking to articles this happens a lot to other softwares. Even though for simulations R&h proposed this trick for numerical approach, the diffusion we get in k (and not the perfect profile as inlet) is casually similar what happen in nature...
One thing that most recent articles avoid to apply is the retarding shear on 1st cell centers that recommended R&H, also R&H recommended to apply face discretization in gradients, something that I have not tried yet
If you want to discuss any related to ABL or AD, I'm open to that!

Originally Posted by Teresa Sun

According to this merge requesthttps://develop.openfoam.com/Develop...e_requests/354, the current ABL boundary conditions are limited to the Neutral-stratified situation.
Does anyone know if these BCs are extended to stable and unstable stratification?