Overview

NinjaFOAM is a new optional solver in WindNinja that solves the conservation of mass and momentum equations. It is based on the OpenFOAM computational fluid dynamics (CFD) toolbox. OpenFOAM is free, open source software for CFD from the OpenFOAM Foundation.

NinjaFOAM

This page documents the individual steps in a NinjaFOAM simulation. These steps are executed in ninjafoam::simulate_wind(). Output from each OpenFOAM call is written to a log file (e.g., log.checkMesh) in the temporary directory.

  1. A temporary case directory is created and the OpenFOAM case files are written to the temporary directory. The OpenFOAM files are copied from template files located in WINDNINJA_DATA/ninjafoam.zip.

  2. The DEM is converted to binary STL format and written to constant/triSurface.

  3. Call surfaceTransformPoints. This creates an STL of the output surface. This is a surface shifted to the user-specified output wind height. It is written to constant/triSurface/<demBaseName>_out.stl.

  4. Call surfaceCheck. This performs a check on the generated STL and writes a file called log.json which is later used in the blockMeshDict file writing if a DEM is not available (e.g., runs initiated with an STL).

  5. Write blockMeshDict. During this step, xmin, xmax, ymin, ymax, zmin, zmax are read/calculated from the DEM unless the run was initiated with an STL file, in which case the necessary terrain information is read from log.json. This is the bounding box for blockMesh.

  6. Run blockMesh.

  7. Run moveDynamicMesh, in parallel if more than once processor is available.

  8. Refine the near-surface layer with refineMesh. This refines the near-surface cells in all directions.

  9. Call checkMesh to check the current cell count. Repeat 8-9 until cell count meets our threshold.

  10. Call renumberMesh.

  11. Call applyInit. This applies the initial conditions.

  12. Run simpleFoam, in parallel if more than one processor is available.

  13. Call sample to sample the velocity field at the user-specified output height. The sampling is controlled by sampleDict. The sampling is performed on the output surface <demBaseName>_out.stl created at the beginning of the simulation. There are several types of interpolation schemes available: cell, cellPoint, cellPointFace, etc.

  14. Convert the raw xyz output to the requested WindNinja formats.

  15. Remove the temporary directory and all OpenFOAM case files unless VTK output was requested.

Documentation


Debugging

Meshing

Refine Mesh