SOWFA Tutorial

Wind & Water Computer-Aided Engineering Software Tools
1

Hey everyone,

I am trying to learn SOWFA as I think it quite an interesting tool to use. However, I am struggling to use it, especially coupling ABL precursor to wind turbine and wind farm simulation. Indeed in tutorials some files are missing, making it really difficult to understand how to make everything work…
For example, the precursor directory (/projects/precursor/neutral3x3) haven’t been added due to its size apparently:

Problem is that I do not know how this files look like, how to create them, … But they are completely necessary to set precursor datas for wind farm simulation:

I want to try to run example.ALM. What I did so far is:
-1) run example.ABL.flatTerrain.neutral from 0 to 20000s with ABLSolver (no problem here)
-2) run again example.ABL.flatTerrain.neutral from 20000s to 22000s with a smaller timestep and with boundaryDataPre function enable.
-3) with boundaryDataPre I found a python script that is able to construct boundaryData. You can find it there: [url]https://github.com/OffWind/offwind/tree/master/Offwind.App/Offwind.Wpf/Templates/precursorABL/neutral[/url]
So far I think these boundary data are what I was looking for. But for sources, I have no idea of how to proceed.
-4) I copied the mesh from the precursor and refined locally the turbines areas. I linked the boundaryData. I used changeDictionary utility to change boundaries from cyclic to inflow/outflow.
-5) As I didn’t get the sources files I tried an other way to make it work using mapFields utility but for now I didn’t succeed to make it work. Here is my way to proceed if some are interested:

If someone has already managed to run the tutorials, all of them, I’m interested to know how you did. I basically just need the method to create the precursor directory.

By the way, my project is to manage to simulate wind farm in complex terrain, and see the impact of wake on the production.

Thanks for your time,
Guillaume Doguet.

2

Problem solved.

3

hi Guillaume, can you post your solution? I am sure it will be helpful for other people who encounter similar problems, thanks!

4

Hey did you by any chance validate your ABL? I also ran the precursor simulation for the Neutral ABL. However when i try to validate it with log-Law, it doesn’t match at some point.

5

Hi Guillaume, how did you manage to input the sources files? I’d really appreciate any help you can give me, as I’m absolutely stuck at this point!

6

I’m currently trying to use SOWFA/ALMAdvanced to simulate wind farms over complex terrain. However, I’ve noticed that SOWFA version 2.4.x seems to have a limitation – it can only handle flat terrain. As far as I understand, the built-in solver and boundary conditions are not designed for irregular topography.

Has anyone successfully extended SOWFA/ALMAdvanced to work with complex terrain? If so, could you share the approach or modifications needed? For example, do I need to modify the mesh generation, wall stress model, or add terrain-following coordinates? Any guidance or workaround would be greatly appreciated.

7

Hi Houqun,

Please look at the newer version of SOWFA which is at GitHub - NatLabRockies/SOWFA-6 · GitHub. This works with the newer OpenFOAM-6. It has a single solver that can handle complex terrain–we’ve used it routinely for complex terrain. You can place the wind turbines in the complex terrain also. We most routinely use the ALM turbine model that is coupled to OpenFAST, which is a pretty neat capability because then you get all the structural dynamics and controls.

I will warn you that the documentation is not great because there is little to no funding for SOWFA anymore. You can always ask me questions (matt.churchfield@nlr.gov) and I can try to answer them.

Thank you for your interest in SOWFA,

Matt Churchfield