[kokab]

Hi lebec
Just found the first question, para view

[lebc]

Hi kokab,

That's it! After, just select the cellzone corresponding to you disk on "Mesh Parts" and click Apply. Finally, you can create some Slices and see your disk and mesh! =)

Best Regards,
Luis

[kokab]

hello lebc
thank you so much about all your help, I have found that the main work is jut changing diskDir because by this way the direction of thrust will be change respectively, but now my problem is : how can I strengthen the effect of force without changing its value? is there any way for example increasing in the number of AD vectors on the cells?
many thanks,
kokab

[lebc]

I'm not sure if I got it right, but you want to increase/reduce the thrust on the actuator disk? Is that correct? If it is, you need to change the cp, ct and Disk area values on fvOptions, these are the parameters that "control" your thrust.

But first, you need to be sure that the region you are specifying to add the source term is correct, otherwise your problem will not be well defined. Just changing the AD direction is not enough, you have to be sure that you are inserting it on the region where your real device would be (for example, a wind turbine rotated 30 degrees will use different cells than one rotated 90 degrees).

Best Regards,
Luis

[kokab]

Hi dear Luis
thank you very much. yeah I meant increasing the thrust... but I did not understand the second part of your comment " you need to be sure... " you know, I am just a new user and not well done in openFOAM. I would be very thankful if you explain it more...
many thanks and also sorry about my late answer
kokab

[hoemmaria]

Originally Posted by kokab

how can I see the disk region?

You open your case in paraView by typing paraFoam in your terminal window. Select either Clip or Slice to inspect the inside of you geometry. By selecting either wireframe or surface with edges you can see how the mesh is in your disk region.

Hope this helps.

Maria

[kokab]

Hi maria
yeah this is, thank you. but is there any way to change the disk direction in openfoam? toposet? because the diskDir just changes the force direction on the disk

[lebc]

Hi kokab,

Did you check the link I sent you?

You can try to use "source rotatedBoxToCell" or "source cylinderToCell" on your toposetdict, it will depend on the kind of problem you are trying to solve. I believe you can also do it based on a .stl surface, but I never tried it...

Best Regards,
Luis

[kokab]

hi Luis
yes I have checked it but I couldn't implement it for actuator disk. I think I should work on it more...

[redbullah]

Originally Posted by louisgag

Hello again,

Well my problem was simply that I was trying to simulate a rotor using the actuationDiskSource method, I understood this after having tried different settings and looked at the code. So, in the meantime I was also able to successfully run a test case of a wind turbine with the actuationDiskSource, getting both pressure and velocity jumps across the disk using pimpleFoam.

I looked at your case Maria, although I didn't run it because all the files are in the same directory. First thing I note is, as Luis pointed out, you have a null velocity. This means the wind turbine won't do anything... Also, make sure diskDir points downstream behind the turbine, which may already be your case...

I would also suggest using a different inletValue velocity at the outlet than the one used at the actual inlet. The details on this boundary conditions are given here: https://cfd.direct/openfoam/user-guide/boundaries/

Hope this helps, otherwise please upload the case with the actual file/folder structure ;-)

Best Regards,


-Louis

Hi Louis,
Despite all my efforts, I could not make the actuationDiskSource work with pimpleFoam. Would you be so kind to share that case file with us?

[redbullah]

Originally Posted by hoemmaria

@Luis

I think I solved it with the help of your files

Things I changed and observed:

1. I had too few cells for the actuator disk to be seen, it was smaller than the cell i x-direction. Thus, adding snappyHexMesh in that area and make the mesh finer at the disk area helped. Or I could have made the whole mesh finer.
2. I made the actuator disk region definition in topoSetDict a cylinder (like in you example) instead of a box.
3. I made the blockMeshDict to consist of only one box, not two (it was two boxes in the example I had gotten the file from). Not sure if this did any difference on its own, but its more tidy at least.
4. I have added the postprocessing option residuals to controlDict to be able to see if the solution converges. The file that follows is placed in "system". To view the residuals, type: foamMonitor -l postprocessing/residuals/0/residuals.dat.

I have also added my final files if anyone wants to look at them or have similar problems in the future.

Thank you so much for all the help!

Kind regards,
Maria Hoem

Maria, I have run the case you have posted but can not get any reasonable results. Did you, by any chance, changed any settings afterwards?

[louisgag]

Hi,
I did not keep the files, I only ran it to see whether Maria's case would run, and it did, with some modifications I pointed out in the thread. You should be able, with some more effort, to reproduce the behavior.
Regards,

[harshilshah81]

Can you give the commands to be given for running this case?
I am trying i) blockMesh ii) topoSet iii)simpleFoam
But it doesn't work.

Originally Posted by hoemmaria

@Luis

I think I solved it with the help of your files

Things I changed and observed:

1. I had too few cells for the actuator disk to be seen, it was smaller than the cell i x-direction. Thus, adding snappyHexMesh in that area and make the mesh finer at the disk area helped. Or I could have made the whole mesh finer.
2. I made the actuator disk region definition in topoSetDict a cylinder (like in you example) instead of a box.
3. I made the blockMeshDict to consist of only one box, not two (it was two boxes in the example I had gotten the file from). Not sure if this did any difference on its own, but its more tidy at least.
4. I have added the postprocessing option residuals to controlDict to be able to see if the solution converges. The file that follows is placed in "system". To view the residuals, type: foamMonitor -l postprocessing/residuals/0/residuals.dat.

I have also added my final files if anyone wants to look at them or have similar problems in the future.

Thank you so much for all the help!

Kind regards,
Maria Hoem

[Kbshariff]

Hi foamers,

I am simulating tidal turbine using AD source with OpenFoam v2006. I would like to use variable scaling method. How can I specify the velocity at the disc location.


Merci

[Kbshariff]

Hi foamers,

I am simulating a tidal turbine with OFv2006. I want to use the variable_scaling_method to calulate the source term in fvOptions.

I get this error

--> FOAM FATAL ERROR: 
[6] Velocity spatial-averaged on actuator disk is zero.
Please check if the initial U field is zero.
[6] 
[6]     From void Foam::fv::actuationDiskSource::calcVariableScalingMethod(const AlphaFieldType&, const RhoFieldType&, Foam::fvMatrix<Foam::Vector<double> >&) [with AlphaFieldType = Foam::geometricOneField; RhoFieldType = Foam::geometricOneField]
[6]     in file sources/derived/actuationDiskSource/actuationDiskSourceTemplates.C at line 201.
[6]

The variable scaling method is based on local velocity at the disc location which is express as

Variable-scaling method
The model expressions for variableScaling method 

T=0.5ρrefA|Uo⋅n|^2*C∗T
with

CT_star=CT(|Um|/|Uo|)^2

How can I specify Uo at the disc location? based on location

Thank you.

[KimBest]

Hi Kabir,

I am also currently trying to run a simulation using the actuator disk source, using openFoamv2012. Did you have any trouble editting the fvOptions file? It simulates the momentum source but seems to be invariant in it's effect regardless of how I edit the file. For example, if I take the turbineSiting tutorial, completely unaltered, and then switch the diskDir to (-1,0,0) instead of (1,0,0), there is no noticeable change to the results. Similiarly, if I increase C_p and C_t to ridiculously high values (up to say 100) there is also no change. Additionally, if I switch sink to false (from true), simpleFoam returns an IO error with no other explanation.
Do you have any idea what this might be? SHM seems to mesh the turbine area well and topoSet is successfully marking enough cells as momentum sources.

[Kbshariff]

Originally Posted by KimBest

Hi Kabir,

I am also currently trying to run a simulation using the actuator disk source, using openFoamv2012. Did you have any trouble editting the fvOptions file? It simulates the momentum source but seems to be invariant in it's effect regardless of how I edit the file. For example, if I take the turbineSiting tutorial, completely unaltered, and then switch the diskDir to (-1,0,0) instead of (1,0,0), there is no noticeable change to the results. Similiarly, if I increase C_p and C_t to ridiculously high values (up to say 100) there is also no change. Additionally, if I switch sink to false (from true), simpleFoam returns an IO error with no other explanation.
Do you have any idea what this might be? SHM seems to mesh the turbine area well and topoSet is successfully marking enough cells as momentum sources.

Hi Kim,

Using the turbing siting tut by default will give you some good result.

You have to navigate to the disc region and plot along the line (velocity and pressure) in paraview. You can then see the effect of changes you made in fvOptions

[Edgar Alejandro Martínez]

You can use Erik Svenning's explicit-force actuator disc. I generalized it for multiple turbines.

The solver is here: https://github.com/EdgarAMO/multipleDiskSimpleFoam

The example case file is here: https://github.com/EdgarAMO/actuator-disk-farm

[MMRC]

Good day,

Was your issue a low deficit? if it was, the common reason to that happening is because traditional k-epsilon tends to overstimate velocity

Originally Posted by KimBest

Hi Kabir,

I am also currently trying to run a simulation using the actuator disk source, using openFoamv2012. Did you have any trouble editting the fvOptions file? It simulates the momentum source but seems to be invariant in it's effect regardless of how I edit the file. For example, if I take the turbineSiting tutorial, completely unaltered, and then switch the diskDir to (-1,0,0) instead of (1,0,0), there is no noticeable change to the results. Similiarly, if I increase C_p and C_t to ridiculously high values (up to say 100) there is also no change. Additionally, if I switch sink to false (from true), simpleFoam returns an IO error with no other explanation.
Do you have any idea what this might be? SHM seems to mesh the turbine area well and topoSet is successfully marking enough cells as momentum sources.